1 Timothy 4:6

The apostle would have Timothy to instil into the minds of Christians such sentiments as might prevent their being seduced by the judaizing teachers. Observe, Those are good ministers of Jesus Christ who are diligent in their work; not that study to advance new notions, but that put the brethren in remembrance of those things which they have received and heard. Wherefore I will not be negligent to put you always in remembrance of these things, though you knew them, Pe2 1:12. And elsewhere, I stir up your pure minds by way of remembrance, Pe2 3:1. And, says the apostle Jude, I will therefore put you in remembrance, Jde 1:5. You see that the apostles and apostolical men reckoned it a main part of their work to put their hearers in remembrance; for we are apt to forget, and slow to learn and remember, the things of God. - Nourished up in the words of faith and good doctrine, whereunto thou hast attained. Observe, 1. Even ministers themselves have need to be growing and increasing in the knowledge of Christ and his doctrine: they must be nourished up in the words of faith. 2. The best way for ministers to grow in knowledge and faith is to put the brethren in remembrance; while we teach others, we teach ourselves. 3. Those whom ministers teach are brethren, and are to be treated like brethren; for ministers are not lords of God's heritage. I.

— Matthew Henry's Concise Commentary (public domain)

If thou put . . . in remembrance--rather as Greek, "If thou suggest to (bring under the notice of) the brethren," &c. these things--namely, the truths stated in Ti1 4:4-5, in opposition to the errors foretold, Ti1 4:1-3. minister--"servant." nourished up--The Greek is present, not past: "continually being nourished in" (Ti2 1:5; Ti2 3:14-15). the words of faith--rather, "the words of the faith" (compare Ti1 4:12). good doctrine--"the good teaching." Explanatory of "the faith," in opposition to the "teachings of demons" (English Version, "doctrines of devils," Ti1 4:1) which Timothy was to counteract. Compare "sound doctrine" (Ti1 1:10; Ti1 6:3; Tit 1:9; Tit 2:1). whereunto thou hast attained--"the course of which thou hast followed"; hast followed along by tracing its course and accompanying it [ALFORD]. Thou hast begun to follow up [BENGEL]. The same Greek occurs, "thou hast fully known" (Ti2 3:10), "having had perfect understanding" (Luk 1:3). It is an undesigned coincidence that the Greek verb is used only by Paul and Paul's companion, Luke.

— Jamieson-Fausset-Brown Commentary (public domain)