As I besought thee to abide, still at Ephesus,.... Where it seems he now was, being left here by the apostle, and where he was desired by him to continue:when I went into Macedonia; not when he went his first journey there, for Timothy was then along with him, Ac 16:3 and so he seems to be in his journey through it, in Ac 20:3.
It may be this may refer to a journey which Luke has given no account of:that thou mightest charge some, that they teach no other doctrine; than the doctrine of Christ and his apostles; than what had been preached by the apostle at Ephesus, and the saints there had received; than what was agreeably to the Scriptures of truth, and was according to godliness; for all other doctrines must be divers and strange ones: nor would he have them teach in another way, in new words, but hold fast the form of sound words; for new words often produce new doctrines: the apostle perhaps by other doctrine chiefly respects the doctrine of justification by the works of the law.
It seems as if there were some teachers in this place the apostle was suspicious of, or he had heard that they began to innovate in the doctrine of faith; wherefore he desires Timothy to continue a while, in order to be a check on these persons, and to charge them not to introduce any new doctrine; for it was only "some", and not all that taught there, he was so to charge.