It is to be noted what kind of elders are to be especially honoured and rewarded. It is those who toil in preaching and teaching. The elder whose service consisted only in words and discussion and argument is not in question here. Those whom the Church really honoured were the ones who worked to edify and build it up by preaching the truth and by educating the young and the new converts in the Christian way.

(2) It was Jewish law that no one should be condemned on the evidence of a single witness: ‘A single witness shall not suffice to convict a person of any crime or wrongdoing in connection with any offence that may be committed. Only on the evidence of two or three witnesses shall a charge be sustained’ (Deuteronomy 19:15). The Mishnah, the codified Rabbinic law, in describing the process of trial, says: ‘The second witness was likewise brought in and examined. If the testimony of the two was found to agree, the case for the defence was opened.’ If a charge was supported by the evidence of only one witness, it was held that there was no case to answer.

Quoted verse:
Deuteronomy 19:15 but I will read verses 15 through 21.  These scriptures are linked clearly to the instructions in Matthew 18 or the "offending brother resolution instructions."  The God-given concepts are equal.

Deuteronomy 19:15-21
15 One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall the matter be established.
16 If a false witness rise up against any man to testify against him that which is wrong;
17 Then both the men, between whom the controversy is, shall stand before the LORD, before the priests and the judges, which shall be in those days;
18 And the judges shall make diligent inquisition: and, behold, if the witness be a false witness, and hath testified falsely against his brother;
19 Then shall ye do unto him, as he had thought to have done unto his brother: so shalt thou put the evil away from among you.
20 And those which remain shall hear, and fear, and shall henceforth commit no more any such evil among you.
21 And thine eye shall not pity; but life shall go for life, eye for eye, tooth for tooth, hand for hand, foot for foot.

In later times, church regulations laid it down that the two witnesses must be Christian [Spirit-holding firstfruits], for it would have been easy for a malicious non-Christian to make up a false charge against a Christian elder in order to discredit him, and through him to discredit the Church. In the early days, the Church authorities did not hesitate to apply discipline; and Theodore of Mopseuestia, one of the early fathers who lived in the late fourth and early fifth centuries, points out how necessary this regulation was, because the elders were always liable to be disliked and were especially open to malicious attack ‘due to the retaliation by some who had been rebuked by them for sin’. Those who had been disciplined might well seek to get their own back by maliciously charging an elder with some irregularity or some sin.

The fact remains that this would be a happier world – and the Church, too, would be happier – if people would realize that it is nothing less than sin to spread stories of whose truth they are not sure. Irresponsible, slanderous and malicious talk does infinite damage and causes infinite heartbreak, and such talk will not go unpunished by God.

(3) Those who persist in sin are to be publicly rebuked [meaning within the congregation of firstfruits]. That public rebuke had a double value. It sobered sinners into a consideration of their ways, and it made others take care that they did not involve themselves in a similar humiliation. The threat of publicity is no bad thing if it keeps people on the right path, even through fear. A wise leader will know the time to keep things quiet and the time for public rebuke. But, whatever happens, the Church must never give the impression that it is condoning sin.

(4) Timothy is urged to administer his office without favoritism or prejudice. The biblical scholar B. S. Easton writes: ‘The well-being of every community depends on impartial discipline.’ Nothing does more harm than when some people are treated as if they could do no wrong and others as if they could do no right. Justice is a universal virtue, and the Church must surely never fall below the impartial standards which even the world demands.

(5) Timothy is warned not to be too hasty ‘in laying hands on any man’. That may mean one of two things.

(a) It may mean that he is not to be too quick in laying hands on any man to ordain him to office in the Church. Before people gain promotion in business, or in teaching, or in the army or the navy or the air force, they must prove that they deserve it. No one should ever start at the top. This is doubly important in the Church, for those who are raised to high office and then fail in it bring dishonour, not only on themselves, but also on the Church. In a critical world, the Church cannot be too careful in regard to the kind of men and women whom it chooses as its leaders.

(b) In the early Church, it was the custom to lay hands on a sinner who repented, who had given proof of repentance and who had returned to the fold of the Church. It is laid down: ‘As each sinner repents, and shows the fruits of repentance, lay hands on him, while all pray for him.’ The early Church historian Eusebius tells us that it was the ancient custom that repentant sinners should be received back with the laying on of hands and with prayer. If that is the meaning here, it will be a warning to Timothy not to be too quick to receive back anyone who has brought disgrace on the Church, to wait until the individual has shown genuine [repentance and invoking of Godly principles-fruit] and a true determination to live according to that declaration of repentance. That is not for a moment to say that such a person is to be held at arm’s length and treated with suspicion, but rather to be treated with all sympathy and with all help and guidance in the period of probation. But it is to say that membership of the Church is never to be treated lightly, and that people must show their [repentance] for the past and their determination for the future before they are received not into the fellowship of the Church but into its membership. The fellowship of the Church exists to help such people redeem themselves, but its membership is for those who have truly pledged their lives to Christ. ~Barclay Commentary

This verse for today, verse 18,  has three phrases:

1] For the scripture saith.
2] Thou halt not muzzle the ox that treadeth out the corn.
3] And the labourer is worthy of his reward.

Let us first get the overall from the Matthew Henry Concise commentary:

This commentary is covering verses 17-25.

Care must be taken that ministers are maintained. And those who are laborious in this work are worthy of double honour and esteem. It is their just due, as much as the reward of the labourer. The apostle charges Timothy solemnly to guard against partiality. We have great need to watch at all times, that we do not partake of other men's sins. Keep thyself pure, not only from doing the like thyself, but from countenancing it, or any way helping to it in others. The apostle also charges Timothy to take care of his health. As we are not to make our bodies masters, so neither slaves; but to use them so that they may be most helpful to us in the service of God. There are secret, and there are open sins: some men's sins are open before-hand, and going before unto judgment; some they follow after. God will bring to light the hidden things of darkness, and make known the counsels of all hearts. Looking forward to the judgment-day, let us all attend to our proper offices, whether in higher or lower stations, studying that the name and doctrine of God may never be blasphemed on our account. ~Matthew Henry Concise commentary

Now that we have seen the concise commentary of Matthew Henry, let us go to the larger version:

I. Concerning the supporting of ministers. Care must be taken that they be honourably maintained (1Timothy 5:17): Let the elders that rule well be counted worthy of double honour (that is, of double maintenance, double to what they have had, or to what others have), especially those who labour in the word and doctrine, those who are more laborious than others. Observe, The presbytery ruled, and the same that ruled were those who laboured in the word and doctrine: they had not one to preach to them and another to rule them, but the work was done by one and the same person. Some have imagined that by the elders that rule well the apostle means lay-elders, who were employed in ruling but not in teaching, who were concerned in church-government, but did not meddle with the administration of the word; and I confess this is the plainest text of scripture that can be found to countenance such an opinion. But it seem a little strange that mere ruling elders should be accounted worthy of double honour, when the apostle preferred preaching to baptizing, and much more would he prefer it to ruling the church; and it is more strange that the apostle should take no notice of them when he treats of church-officers; but, as it is hinted before, they had not, in the primitive church, one to preach to them and another to rule them, but ruling and teaching were performed by the same persons, only some might labour more in the word and doctrine than others.

Here we have,

1. The work of ministers; it consists principally in two things: ruling well and labouring in the word and doctrine. This was the main business of elders or presbyters in the days of the apostles.

2. The honour due to those who were not idle, but laborious in this work; they were worthy of double honour, esteem, and maintenance. He quotes a scripture to confirm this command concerning the maintenance of ministers that we might think foreign; but it intimates what a significancy there was in many of the laws of Moses, and particularly in this, Thou shalt not muzzle the ox that treads out the corn, Deuteronomy 25:4. The beasts that were employed in treading out the corn (for that way they took instead of threshing it) were allowed to feed while they did the work, so that the more work they did the more food they had; therefore let the elders that labour in the word and doctrine be well provided for; for the labourer is worthy of his reward (Matthew 10:10), and there is all the reason in the world that he should have it.

We hence learn,

(1.) God, both under the law, and now under the gospel, has taken care that his ministers be well provided for. Does God take care for oxen, and will he not take care of his own servants? The ox only treads out the corn of which they make the bread that perishes; but ministers break the bread of life which endures for ever.

(2.) The comfortable subsistence of ministers, as it is God's appointment that those who preach the gospel should live of the gospel (1 Corinthians 9:14), so it is their just due, as much as the reward of the labourer; and those who would have ministers starved, or not comfortably provided for, God will require it of them another day.

Quoted scriptures:
Deuteronomy 25:4
Thou shalt not muzzle the ox when he treadeth out the corn.

Matthew 10:10
Nor scrip for your journey, neither two coats, neither shoes, nor yet staves: for the workman is worthy of his meat.

1 Corinthians 9:14
Even so hath the Lord ordained that they which preach the gospel should live of the gospel.

1] For the scripture saith.

For the Scripture saith - This is adduced as a reason why a church should show all due respect and care for its ministers. The reason is, that as God took care to make provision for the laboring ox, much more should due attention be paid to those who labor for the welfare of the church. ~Barnes Notes

To me the most remarkable element in this phrase is that Paul was always, in his spiritual writing, referring either to direct scripture or making spiritual conclusion based on both biblical principles and spirit-driven logic or unction of the Holy Spirit [1 John 2:20]. We see in the commentaries, a number of times that Paul adduced something from scripture. "Adduced" means to cite as an example or means of proof in an argument, teaching or discussion. This is what all firstfruits are doing. You are out there in the world making a multitude of decisions every day. Some are routine and some are important or even life-changing. We are to make all decisions based on spiritual and moral principles.

Notice some quotes on making wise decisions. You will see they originate in spiritual and moral principles.

“Let me not hurt, by any selfish deed, Or thoughtless word, the heart of foe or friend; Nor would I pass, unseeing, worthy need, Or sin by silence when I should defend... 'The world is better that I lived to-day.'”

“Each day when I awake I know I have one more day to make a difference in someone's life.”

“Be careful of your actions. You never know when your creating a memory.”

“Every thought is a seed. If you plant crab apples, don't count on harvesting Golden Delicious.”

"There are three constants in life... change, choice and principles."

Proverbs 12:15
The way of a fool is right in his own eyes: but he that hearkeneth unto counsel is wise.

Proverbs 3:5-6
5 Trust in the LORD with all thine heart; and lean not unto thine own understanding.
6 In all thy ways acknowledge him, and he shall direct thy paths.

2] Thou halt not muzzle the ox that treadeth out the corn.

Barnes Notes:
The Scripture saith, Thou shalt not muzzle the ox - This is a manifest proof that by τιμη, honor, in the preceding verse, the apostle means salary or wages: “Let the elders that rule well be accounted worthy of double honor,” a larger salary than any of the official widows mentioned before, for “the laborer is worthy of his hire.” The maintenance of every man in the Church should be in proportion to his own labor, and the necessities of his family. He that does no work should have no wages. In the Church of Christ there never can be a sinecure [A position or office that requires little or no work but provides a salary]. They who minister at the altar should live by the altar; the ox that treadeth out the corn should not be muzzled; the laborer is worthy of his hire: but the altar should not support him who does not minister at it; if the ox won’t tread out the corn, let him go to the common or be muzzled; if the man will not labor, let him have no hire. ~Barnes Notes

John Gill ...and I really like what this one has to say:
The Scripture saith, Thou shalt not muzzle the ox - The ox, for its strength and labour, is a fit emblem of a Gospel minister; and its treading the corn out of the husk and ear aptly represents the beating out, as it were, of Gospel truths, by the ministers of it, their making the doctrines of the Gospel clear, plain, and evident to the understandings of men; wherefore, as the ox was not muzzled when it trod out the corn, but might freely and largely feed upon it, so such who labour in the preaching of the Gospel ought to have a sufficient and competent maintenance: for which purpose this citation is made. ~John Gill

3] And the labourer is worthy of his reward.

Barnes Notes:
And, The labourer is worthy of his reward - This expression is found substantially in Matthew 10:10, and Luke 10:7. It does not occur in so many words in the Old Testament, and yet the apostle adduces it evidently as a quotation from the Scriptures, and as authority in the case. It would seem probable, therefore, that he had seen the Gospel by Matthew or by Luke, and that he quoted this as a part of Scripture, and regarded the Book from which he made the quotation as of the same authority as the Old Testament. If so, then this may be regarded as an attestation of the apostle to the inspiration of the “Gospel” in which it was found. ~Barnes Notes

Quoted verses:
Matthew 10:10 ...referenced above
Nor scrip for your journey, neither two coats, neither shoes, nor yet staves: for the workman is worthy of his meat.

Luke 10:7
And in the same house remain, eating and drinking such things as they give: for the labourer is worthy of his hire. Go not from house to house.

John Gill:
And the labourer is worthy of his reward - which seems to be taken from Luke 10:7 [above] which Gospel was now written, and in the hands of the apostle; who here, by two testimonies, the one from Moses, and the other from Christ, supports the right of the honourable maintenance of the ministers of the Gospel. ~John Gill

What we learn in this lesson:

1] This verse is speaking to preaching and teaching elders of the church.
2] Care must be taken that ministers are maintained.

3] Ministers are to guard against partiality.
4] Ministers are to take care of their health.

5] Study that the name and doctrine of God may never be blasphemed on our account.
6] All firstfruits should make decisions based on the Word of God and spiritual and moral principles.

7] Acknowledge God in all your ways and He will direct your paths.
8] The ox, for its strength and labour, is a fit emblem of a Gospel minister.