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.

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, Acts. i. scen. 2, ver. 47.
Thou art his father by nature, I by instruction.

Salute Rufus chosen in the Lord,.... This was a Roman name; frequent mention is made Jewish writings (u) of one Turnus Rufus, a Roman officer, that destroyed the temple, and ploughed up the city of Jerusalem; the name was in use among the Cyrenians, for one of the sons of Simon of Cyrene, whom the Jews compelled to carry the cross of Christ, was so called, Mark 15:21; and some have thought that the same person is here meant, nor is it unlikely; he is said to be one of the seventy disciples, and to be bishop of Thebes; See Gill on Luke 10:1. The apostle knew him, and that as one "chosen in the Lord"; meaning either that he was a choice believer in Christ, an excellent Christian, one of the highest form; for though all true believers have like precious faith, yet some are strong, and others weak, in the exercise of it; this man was eminent for his faith in Christ: or he might be one that was chosen to some office in the church, as to that of a deacon, or pastor; though had this been the case, it is much the particular office was not mentioned: rather therefore this is to be understood of his being chosen in Christ to grace and glory and that from all eternity; for the phrase is only used in one place more, Ephesians 1:4; and there most manifestly designs the election of persons in Christ, before the foundation of the world; which election is made not "for" Christ, or the sake of his merits, his blood, righteousness and sacrifice, which have no causal influence on this act, and which purely arises from the love and grace of God; nor merely "by" him as God equal with the Father, though this is true; but "in" him, as the head and representative of the chosen ones: this instance, as others, shows that election is not of nations, nor churches, but of particular persons; and so expresses the distinguishing, free, and sovereign grace of God in it, that one and not another should be chosen; though these are on an equal foot, and so not owing to foreseen faith, holiness, and good works. The apostle knew this man to be a chosen vessel, not by immediate revelation, or divine inspiration, but by his faith in Christ, and love to him, and by the power of the Gospel on him; and so may anyone know himself, or another man hereby to be chosen, and ought in a judgment of charity so to think of him, as long as his life is agreeably to his profession; see 1-Thessalonians 1:4. The apostle not only salutes this man, but his mother also, who doubtless was a believer in Christ, and highly respected by him:
and his mother and mine; the mother of Rufus in nature, and his mother in affection; and who very probably had endeared herself to the apostle by some kind offices, which she, as a Christian, had performed towards him; for the apostle cannot mean his own natural mother, besides Rufus's, whom he salutes, and whom Anselm on the place suggests might be at Rome; since it can hardly be thought he would have passed the mention of her in so transient a manner.
(u) T. Hieros. Taanioth, fol. 69. 2. T. Bab. Nedar. fol. 50. 2. Avoda Zara, fol. 20. 1. & Sanhedrin, fol. 65. 2. Juchasin, fol. 36. 2.

Salute Rufus, chosen--"the chosen"
in the Lord--meaning, not "who is one of the elect," as every believer is, but "the choice" or "precious one" in the Lord. (See 1-Peter 2:4; 2-John 1:13). We read in Mark 15:21 that Simon of Cyrene, who was compelled to bear our Lord's cross, was "the father of Alexander and Rufus." From this we naturally conclude that when Mark wrote his Gospel, Alexander and Rufus must have been well known as Christians among those by whom he expected his Gospel to be first read; and, in all likelihood, this was that very "Rufus"; in which case our interest is deepened by what immediately follows about his mother.
and--salute.
his mother and mine--The apostle calls her "his own mother," not so much as our Lord calls every elderly woman believer His mother (Matthew 12:49-50), but in grateful acknowledgment of her motherly attentions to himself, bestowed no doubt for his Master's sake, and the love she bore to his honored servants. To us it seems altogether likely that the conversion of Simon the Cyrenian dated from that memorable day when "passing [casually] by, as he came from the country" (Mark 15:21), "they compelled him to bear the" Saviour's cross. Sweet compulsion, if what he thus beheld issued in his voluntarily taking up his own cross! Through him it is natural to suppose that his wife would be brought in, and that this believing couple, now "heirs together of the grace of life" (1-Peter 3:7), as they told their two sons, Alexander and Rufus, what honor had unwittingly been put upon their father at that hour of deepest and dearest moment to all Christians, might be blessed to the inbringing of both of them to Christ. In this case, supposing the elder of the two to have departed to be with Christ ere this letter was written, or to have been residing in some other place, and Rufus left alone with his mother, how instructive and beautiful is the testimony here borne to her!

Salute Rufus - Perhaps the same that is mentioned, Mark 15:21. And his mother and mine - This expression may only denote the tender care which Rufus's mother had taken of him.