2 Timothy 3:10

“But thou hast fully known my doctrine, etc.] This, with what follows, is said in opposition to the characters, principles, and practices of the above wicked men, and for the imitation and encouragement of Timothy, and of others, whether ministers or private believers: the apostle calls the doctrine he delivered, “my doctrine”: not because he was the author of it, or that it was a scheme of principles formed and contrived by him; but because it was the doctrine which he had received from God, which was given him to preach, and which he did preach purely and faithfully; otherwise it was the doctrine of Christ, and the same with that which was preached by the rest of the apostles; and which was…”

“fully known--literally, "fully followed up" and traced; namely, with a view to following me as thy pattern, so far as I follow Christ; the same Greek as in Luk 1:3, "having had perfect understanding of all things." His pious mother Eunice and grandmother Lois would recommend him to study fully Paul's Christian course as a pattern. He had not been yet the companion of Paul at the time of the apostle's persecutions in Antioch, Iconium, and Lystra (Act 13:50; Act 14:5, Act 14:19), but is first mentioned as such Act 16:1-3. However, he was "a disciple" already, when introduced to us in Act 16:1-3; and as Paul calls him "my own son in the faith," he must have been converted by the apostle…”

“But thou hast fully known my doctrine ... - Margin, “been a diligent follower of.” The margin is more in accordance with the usual meaning of the Greek word, which means, properly, to accompany side by side; to follow closely; to trace out; to examine Luke 1:3, and to conform to. The meaning here, however, seems to be, that Timothy had an opportunity to follow out; i. e., to examine closely the manner of life of the apostle Paul. He had been so long his companion, that he had had the fullest opportunity of knowing how he had lived and taught, and how he had borne persecutions. The object of this reference to his own life and sufferings is evidently to encourage Timothy to bear persecutions…”

“thou hast fully known: or, thou hast been a diligent follower of, Luk 1:3; Phi 2:22; Ti1 4:6 \*Gr. my: Ti2 3:16, Ti2 3:17, Ti2 4:3; Act 2:42; Rom 16:17; Eph 4:14; Ti1 1:3, Ti1 4:12, Ti1 4:13; Tit 2:7; Heb 13:9; Jo2 1:9, Jo2 1:10 manner: Act 20:18, Act 26:4; Th1 1:5; Pe2 3:11 purpose: Dan 1:8; Act 11:23; Co2 1:17 faith: Ti2 2:22; Co2 6:4-10; Ti1 4:12, Ti1 6:11; Pe2 1:5-7 2 Timothy 3:11”