But {1} speak thou the things which become sound doctrine:

(1) The fifth admonition: the doctrine must not only be generally pure, but also be applied to all ages and orders of men, according to the diversity of circumstances.

People's New Testament

Titus 2:1 Practical Duties Versus Unsound Doctrine

SUMMARY OF TITUS 2:

Duties of the Aged. Of the Young Men and Women. Of Servants. Christian Life. Christian Hope.

Speak... sound doctrine. Instead of inculcating Jewish fables and speculations, impart healthy teaching; teach practical duties.

Wesley's Notes

2:1 Wholesome - Restoring and preserving spiritual health.

Jamieson-Fausset-Brown Bible Commentary

CHAPTER 2

Tit 2:1-15. Directions to Titus: How to Exhort Various Classes of Believers: The Grace of God in Christ Our Grand Incentive to Live Godly.

1. But . thou-in contrast to the reprobate seducers stigmatized in Tit 1:11, 15, 16. "He deals more in exhortations, because those intent on useless questions needed chiefly to be recalled to the study of a holy, moral life; for nothing so effectually allays men's wandering curiosity, as the being brought to recognize those duties in which they ought to exercise themselves" [Calvin].

speak-without restraint: contrast Tit 1:11, "mouths . stopped."

doctrine-"instruction" or "teaching."

Matthew Henry's Concise Commentary

2:1-8 Old disciples of Christ must behave in every thing 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 endeavour 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!