John Calvin Commentary Colossians 4:10

"Aristarchus my fellow-prisoner saluteth you, and Mark, the cousin of Barnabas (touching whom ye received commandments; if he come unto you, receive him)," — Colossians 4:10 (ASV)

Fellow-prisoner. From this it appears that there were others who were associated with Paul after he was brought to Rome. It is also probable that his enemies initially exerted themselves to deter all pious persons from helping him by threatening them with similar danger. For a time, this had the desired effect. But afterwards, some, gathering courage, despised everything held out to them as a terror.

That you receive him. Some manuscripts have receive in the imperative mood; but it is a mistake, because he expresses the nature of the charge the Colossians had received—namely, that it was a commendation of either Barnabas or Marcus. The latter is more probable. In Greek, it is the infinitive mood, but it may be translated as I have done. Let us, however, observe that they were careful in providing attestations, so that they might distinguish good men from false brethren—from pretenders, impostors, and multitudes of vagrants. This same care is all the more necessary today, both because good teachers are received coldly and because credulous and foolish people make themselves too vulnerable to being deceived by impostors.