Rufus, chosen in the Lord - Τον εκλεκον, one of great excellence in Christianity; a choice man, as we would say. So the word εκλεκτος often signifies. Psalm 78:31; : They smote τους εκλεκτους, the chosen men that were of Israel. So εκλεκτα μνημεια are choice sepulchres, Genesis 23:6; : εκλεκτα των δωρων choice gifts, Deuteronomy 12:11; and ανδρες εκλεκτοι, choice men, Judges 20:16. By the same use of the word, the companions of Paul and Barnabas are termed chosen men, εκλεξαμενους ανδρας, persons in whom the Church of God could confide. See Whitby.
His mother and mine - It is not likely that the mother of Rufus was the mother of Paul; but while she was the natural mother of the former, she acted as a mother to the latter. We say of a person of this character, that she is a motherly woman. Among the ancients, he or she who acted a kind, instructing, and indulgent part to another, was styled the father or mother of such a one. So Terence: -
Natura tu illi pater es, consiliis ego.
Adelphi, Act. i. scen. 2, ver. 47.
Thou art his father by nature, I by instruction.
Chosen in the Lord - “Elect” in the Lord; that is, a chosen follower of Christ.
And his mother and mine - “His mother in a literal sense, and mine in a figurative one.” An instance of the delicacy and tenderness of Paul; of his love for this disciple and his mother, as if he were of the same family. Religion binds the hearts of all who embrace it tenderly together. It makes them feel that they are one great family, united by tender ties, and joined by special attachments. See what the Lord Jesus declared in Matthew 12:47-50, and his tender address to John when he was on the cross; John 19:26-27.