Aristarchus my fellowprisoner saluteth you, and Marcus, sister's son to Barnabas, (touching whom ye received commandments: if he come unto you, receive him;) Aristarchus my fellow prisoner - Concerning Aristarchus, see Acts 19:29; Acts 20:4; Acts 27:2; and see the note on Acts 27:2. Aristarchus and Epaphras are mentioned as saluters in this epistle, and in that to Philemon written at the same time; but here he is said to be a prisoner, and Epaphras not. In that to Philemon, Epaphras is called a prisoner, and Aristarchus not. One of them is wrong, though it is uncertain which; unless both were prisoners. See Wall's Crit. Notes. As Aristarchus had been a zealous and affectionate adherent to St. Paul, and followed him in all his journeys, ministering to him in prison, and assisting him in preaching the Gospel in Rome, he might have been imprisoned on this account. We need not suppose that both he and Epaphras were imprisoned at the same time; about the same time they might be imprisoned, but it might be so ordered by the providence of God that when Aristarchus was imprisoned Epaphras was at liberty, and while Epaphras was in prison Aristarchus was at liberty. This is a very possible and easily to be conceived case.
Marcus - See the account of this person, Acts 15:39. Though there had been some difference between the apostle and this Mark, yet from this, and 2 Timothy 4:11, we find that they were fully reconciled, and that Mark was very useful to St. Paul in the work of the ministry.
Touching whom ye received commandments - What these were we cannot tell; it was some private communication which had been previously sent to the Colossian Church.