This section has two verses:

Titus 2:9-10
9 Exhort servants to be obedient unto their own masters, and to please them well in all things; not answering again;
10 Not purloining, but shewing all good fidelity; that they may adorn the doctrine of God our Saviour in all things.

We will begin with the Barclay commentary.

THE CHRISTIAN CHARACTER
6. THE CHRISTIAN WORKER

Titus 2:9–10 ...paraphrased
Impress upon slaves the duty of obeying their own masters. Urge them to seek to give satisfaction in every task, not to answer back, not to pilfer [steal], but to display all fidelity [loyalty] with hearty goodwill, that they may in all things adorn the teaching which God our Saviour gave to them.

In the early Church, the problem for Christian workers was acute. It was one which could operate in two directions.

If the master was not a Christian, the responsibility laid upon servants was heavy indeed, for it was perhaps only through their conduct that the master could ever come to see what Christianity was. It was the task of the workers to show the master what a Christian could be; and that responsibility still lies upon Christian employees. A large number of people never willingly darken a church door, a minister of the church seldom gets a chance to speak to them. How then is Christianity ever to make contact with them? The only possible way is for colleagues at work to show them what Christianity is. There is a famous story of Francis. One day, he said to one of the young monks: ‘Let us go down to the village and preach to the people.’ So they went. Every so often, they stopped to talk to someone. They begged something to eat at one house. Francis stopped to play with the children, and exchanged a greeting with the passers-by. Then they turned to go home. ‘But Father,’ said the novice, ‘when do we preach?’ ‘Preach?’ smiled Francis. ‘Every step we took, every word we spoke, every action we did, has been a sermon.’

There was another side to the problem. If the master was a Christian, a new temptation came into the lives of Christian workers. They might attempt to trade on the master’s Christianity. They might think that, because they were Christians, special allowances would be made for them. They might expect to ‘get away’ with things because they and the master were members of the same church. It is perfectly possible for people to trade on their Christianity – and there is no worse advertisement for it than the person who does that.

Paul lists the qualities of Christian workers.

They are obedient. Christians are never above taking orders. Their Christianity teaches them how to serve. They are efficient. They are determined to give satisfaction. Christian workers can never put less than their best into any task that is given them to do. They are respectful. They do not think that their Christianity gives them a special right to be undisciplined. Christianity does not obliterate the necessary lines of authority in the world of industry and of commerce. They are honest. Others may stoop to the petty dishonesties of which the world is full; but their hands are clean. They are faithful. The master can rely upon their loyalty.

It may well be that those who take their Christianity to work will run into trouble; but, if they stick to it, they will end by winning everyone’s respect.

The missionary E. F. Brown tells of a thing which happened in India. ‘A Christian servant in India was once sent by his master with a verbal message which he knew to be untrue. He refused to deliver it. Though his master was very angry at the time, he respected the servant all the more afterwards and knew that he could always trust him in his own matters.’

The truth is that in the end the world comes to see that the Christian worker is the one most worth having. In one sense, it is hard to be a Christian at our work; in another sense, it is easier than we think, for there is not an employer under the sun who is not desperately looking for employees whose loyalty and efficiency can be relied upon. ~Barclay Commentary

Now to the other commentaries beginning with the general and going to the specific.

Let us begin with the Matthew Henry Main commentary. The commentary covers verses 1-10 in one long text. We will break in where it begins speaking of verse 10.
 
[4.] Not purloining, but showing all good fidelity. This is another great essential of good servants, to be honest, never converting that to their own use which is their master's, nor wasting the goods they are entrusted with; that is, purloining. They must be just and true, and do for their masters as they would or should for themselves. Proverbs 28:24, Whoso robbeth his father or his mother, and saith, It is no transgression, the same is the companion of a destroyer; he will be ready to join with him. Thus, having such light thoughts of taking beyond what is right, though it be from a parent or master, is likely to harden conscience to go further; it is both wicked in itself, and it tends to more. Be it so that the master is hard and strait, scarcely making sufficient provision for servants; yet they must not be their own carvers, nor go about by theft to right themselves; they must bear their lot, committing their cause to God for righting and providing for them. I speak not of cases of extremity, for preserving life, the necessaries for which the servant has a right to. Not purloining, but showing all good fidelity; he must not only not steal nor waste, but must improve his master's goods, and promote his prosperity and thriving, to his utmost. He that increased not his master's talent is accused of unfaithfulness, though he had not embezzled nor lost it. Faithfulness in a servant lies in the ready, punctual, and thorough execution of his master's orders; keeping his secrets and counsels, dispatching his affairs, and managing with frugality, and to as much just advantage for his master as he is able; looking well to his trusts, and preventing, as far as he can, all spoil, or loss, or damage. This is a way to bring a blessing upon himself, as the contrary often brings utter ruin. If you have not been faithful in that which is another man's, who shall give you that which is your own? Luke 16:12. Thus of the duties themselves, to which servants are to be exhorted.

(2.) Here is the consideration with which Titus was to enforce them: That they may adorn the doctrine of God our Saviour in all things; that is, that they may recommend the gospel and Christ's holy religion to the good opinion of those that are without, by their meek, humble, obedient, and faithful conduct in all things. Even servants, though they may think that such as they, in so low and inferior a condition, can do little to bring repute to Christianity, or adorn the doctrine of Christ, and set forth the excellences of his truth and ways, yet, if they be careful to do their duty, it will redound [have good effect] to the glory of God and the credit of religion. The unbelieving masters would think the better of that despised way, which was everywhere spoken against, when they found that those of their servants who were Christians were better than their other servants - more obedient and submissive, more just and faithful, and more diligent in their places. True religion is an honour to the professors of it; and they should see that they do not any dishonour to it, but adorn it rather in all that they are able. Our light must shine among men, so that they, seeing our good works, may glorify our Father who is in heaven. And thus, of the apostle's directions to Titus, about the discharge of his office, in reference to several sorts of persons. ~Matthew Henry Main

Now to the Matthew Henry Concise. This commentary covers verses 1-10.
 
Old disciples of Christ must behave in everything agreeably to the Christian doctrine. That the aged men be sober; not thinking that the decays of nature will justify any excess; but seeking comfort from nearer communion with God, not from any undue indulgence. Faith works by, and must be seen in love, of God for himself, and of men for God's sake. Aged persons are apt to be peevish and fretful; therefore, need to be on their guard. Though there is not express Scripture for every word, or look, yet there are general rules, according to which all must be ordered. Young women must be sober and discreet; for many expose themselves to fatal temptations by what at first might be only want of discretion. The reason is added, that the word of God may not be blasphemed. Failures in duties greatly reproach Christianity. Young men are apt to be eager and thoughtless, therefore must be earnestly called upon to be sober-minded: there are more young people ruined by pride than by any other sin. Every godly man's endeavor must be to stop the mouths of adversaries. Let thine own conscience answer for thine uprightness. What a glory is it for a Christian, when that mouth which would fain open itself against him, cannot find any evil in him to speak of! ~Matthew Henry Concise.

Now some things from the Biblical Illustrator

Not purloining

Honesty in little things
I. The nature of the sin against which the text warns us. Stealing is a term applicable to the conduct of a man who goes to the house, or the farm, or the shop of another, and takes away his goods or other property. We turn an act of theft into one of purloining when a servant helps himself, without an understood allowance from his master or mistress, to that which is under his care, or to which he has access; or when a workman pockets, for his own use, what he thinks he may bear away without detection; or when a labourer carries away from his master’s farm something to add to his own little stock, or to maintain his own family. To steal is to take what is not our own. To purloin is to take what is not our own too; but it is something we had in trust, or to which we had access. If purloining be practiced on a large scale, it changes its name and becomes embezzlement.

II. The exceeding sinfulness of this sin. There are many excuses which are brought forward in extenuation of this offence.
1. The change of its name. There is a wonderful imposition in words; and many purloiners quiet their consciences by changing the name. Because it is not commonly called stealing, they think it does not involve the guilt of stealing.
2. Another plea is, that however great the amount may be in the course of months or years, you are pleased to make the depredations small in detail. It is a petty affair of every day, and so very little as not to be worth thinking about. It does not say, “Thou shalt not steal much!” but, “Thou shalt not steal!”
3. The next plea is, that the master is rich and will not miss it, and so it will do no harm. This law does not merely forbid them to steal from the poor, leaving them at liberty to steal from the rich.

III. The motives which enforce the opposite conduct. The servants whom Titus was to exhort were those of his own congregation. They formed a Christian community; and however the title may be applied now, it was then given to these who had renounced Paganism. The admonition was to men who had embraced not only the profession of faith, but the faith itself. It is right that, for every kind of unrighteousness, men should be reproved; for “the wrath of God is revealed,” etc. The more they are burdened with a sense of sin, the more will they feel the importance of repentance. ~Biblical Illustrator

Fidelity in a servant
Selim, a poor Turk, had been brought up from his youth with care and kindness by his master, Mustapha. When the latter lay at the point of death, Selim was tempted by his fellow servants to join them in stealing a part of Mustapha’s treasures. “No,” said he, “Selim is no robber. I fear not to offend my master for the evil he can do me now, but for the good he has done me all my life long.” ~Biblical Illustrator

That they may adorn the doctrine of God our Saviour
Servants adorning the gospel

I. The doctrine of the gospel: the doctrine of the gospel is called the doctrine of Christ.
1. Because He is the argument and subject of it.
2. Because He is the first and chief messenger and publisher of it.
3. Whosoever have been the teachers and publishers of this doctrine from the beginning, either by word or writing (not excepting prophets or apostles themselves) or shall be unto the end. They all do it by commandment from Him, yea, Himself preacheth in them and in us.
4. As it proceedeth from Him so it tendeth wholly unto Him, and leadeth believers to see and partake both of His grace and glory shining in the same.

II. Christ is called God our Saviour.
1. To prove His own deity, not only in express terms being called God, but also by the epithet [word or phrase applied to a person] agreeing only to a Divine nature, our Saviour.
2. To imply our own misery, whose infinite wretchedness only God could remove, and whose infinite good none but God could restore.
3. And especially in regard of this doctrine.

(1) To confirm the divinity of the same, it being a doctrine of God and a doctrine of salvation proceeding from our Saviour.
(2) To enforce the duty towards it, namely, that seeing the author of it is God, the matter Divine, the effect salvation, meet it is that such a saving doctrine a doctrine of such tidings, should be beautified and adorned.

III. This doctrine is adorned when it is made beautiful and lovely unto men, and this by two things in the professors of it.
1. By an honest and unblamable conversation, for carnal men commonly esteem of the doctrine by the life, and the profession by the practice of the professor.

2. By God’s blessing which is promised and is attending such walking, whereby even strangers to the Church are forced to begin to like of the profession: for God’s blessing upon His people is not only profitable to themselves, but turneth to the salvation of many others.

IV. Servants adorn the gospel, when professing it, they, by performing all faithful service to their masters in and for God, seek and obtain the blessing of God in the condition of life wherein He hath placed them. ~Biblical Illustrator

The duty of advancing the Christian religion
I. The explanation of the terms used.
1. By “the doctrine of God our Saviour” the apostle means the Christian religion, or that institution of faith and manners which Jesus taught and published when here on earth.
2. To “adorn the doctrine of God our Saviour” is to advance the credit and reputation of Christian religion in the world. It is so to govern and demean ourselves that we may reconcile its enemies to a good opinion of it; that we may procure and even force regard and veneration towards it.
3. By the “they” in the text, the persons upon whom this duty is incumbent, we may fairly understand the whole body of Christians.

II. The nature, acts, and exercises of duty. How a man may adorn the doctrine of God our Saviour
1. As it is a rule of faith, or an institution of religion, which we believe and own as of Divine authority. By manifesting, beyond any reasonable exception, that we unfeignedly assent unto it, that we firmly believe it to be, what we pretend, of Divine original. And this will be evident to all

(1) If our faith be perfect and entire. If we receive our religion as it is in itself, in all its parts, in every article, and in their plainest sense.
(2) If we are steady, firm, and constant in the profession of it.
(3) If we express an affection, a prudent zeal in the profession of it.

2. As it is a rule of life and manners. To this purpose it is absolutely necessary
(1) That our obedience be entire and universal.
(2) That our obedience be free and cheerful,
(3) If in cases doubtful we determine our practice on the side of the law, and of our duty.
(4) By an eminent practice of some particular virtues, as of mercy and charity. Wherever these are expressed to the life—habitually, bountifully, freely—all that observe it will esteem the religion from whence such a spirit flows.

III. The reasons which oblige us, and the encouragements which may persuade us, to the practice of it.
1. To adorn the doctrine of God our Saviour by such a faith and practice as I have now described is the most infallible assurance, both to ourselves and others, that our principle is sincere and perfect.
2. To live such a life as shall cause our religion to be esteemed and honoured in the world, is the greatest blessing, as well to ourselves as to others, that we can either imagine or desire.
3. Another encouragement to such a profession and practice of our religion as shall adorn it are the particular promises which are made to those who shall attain unto it.
4. The particular peace and satisfaction which will arise from such a faith and life. ~Biblical Illustrator

So:
1] Do not steal.
2] Do not use anything without authority or permission.
3] Adorn the doctrine and gospel of God.
4] Do good works.
5] Be a light in everything you do.
6] Invoke assiduity.
7] Be a good servant.

These are the lessons of verse 10