Jamieson, Fausset and Brown on 2 Timothy 2:11

11. Greek, "Faithful is the saying."

For--"For" the fact is so that, "if we be dead with Him (the Greek aorist tense implies a state once for all entered into in past times at the moment of regeneration, Ro 6:3, 4, 8; Col 2:12), we shall also live with Him." The symmetrical form of "the saying," 2Ti 2:11-13, and the rhythmical balance of the parallel clauses, makes it likely, they formed part of a Church hymn (see on 1Ti 3:16), or accepted formula, perhaps first uttered by some of the Christian "prophets" in the public assembly (1Co 14:26). The phrase "faithful is the saying," which seems to have been the usual formula (compare 1Ti 1:15; 3:1; 4:9; Tit 3:8) in such cases, favors this.