1 Timothy 1:3

As I exhorted thee to tarry at Ephesus, when I was going into Macedonia, that thou mightest charge certain men not to teach a different doctrine.

It is not improbable that on his last trip to Rome, Paul covered as much ground as he could, warning and encouraging the many churches that he had planted concerning the looming persecutions in Rome. The thing that most concerned Paul was that the doctrine should be maintained absolutely in its purity and fidelity. The situation at Ephesus, where Paul had lately been, was compounded by the appearances of certain departures from the true faith, and this letter was Paul's charge to Timothy relative to making the necessary corrections. It appears that Paul was compelled, from whatever consideration we do not know, to proceed with all dispatch to Rome; hence the reason for his leaving Timothy behind at Ephesus.

Tarry at Ephesus ... In the Greek, this is "stay on,"[14] and, as Hendriksen said, this probably indicates that Paul and Timothy had gone to Ephesus together, Timothy being left behind when Paul could no longer stay.

Certain men ... The indication from this is that not a great number were involved, but that some false teachings were being advocated. Their importance, by these admonitions, is not indicated as a very big thing; but all false teaching should be cut off at the beginning wherever possible.

Not to teach a different doctrine ... The false doctrine in evidence here "seems to have arisen mainly, if not entirely, from Jewish sources."[15] Apparently, some new phases of Jewish error had surfaced at Ephesus, indicating the passage of some time, intervening between this and Paul's earlier letters; but there is absolutely no indication that some remote later period in the late first or early second centuries is in view. The only thing proved by this is that "Paul's forebodings for the church in Ephesus (Acts 20:29,30) were at that time being fulfilled."[16] Wesley's quaint interpretation here is, "Let them put nothing in the place of it (the gospel), and add nothing to it."[17]

[14] William Hendriksen, op. cit., p. 54.

[15] H. D. M. Spence, op. cit., p. 178.

[16] Newport J. D. White, op. cit., p. 91.

[17] John Wesley, op. cit., in loco.