New commandment
1 Corinthians 9:21
I may have miscategorized 1Co 9:21 here. The phrase “Law of Christ” is thrown out almost in passing, and it may be more about a moral law than about anything specific, whereas in Gal 6:2 it seems more plausibly connected to the new commandment, loving one another. However, scholarly consensus (even among critics) is that both letters are authentically Pauline and, of the two, Galatians was written earlier. So if Paul had established a technical meaning for “Law of Christ” by the time he wrote Galatians, he would likely still be using that technical meaning even if he only mentions it in passing in 1 Corinthians.
Related?
Are these related to the new commandment?
The (second) greatest commandment
Mt 22:37–40 (cf. Mk 12:29–31; Lk 10:27–28); Ro 13:8–10; Gal 5:14
The golden rule
Love your enemies
Mt 5:43–48 (cf. Lk 6:27–36) — this is also not new; cf. Lev 19:33–34 (cf. Ex 22:21; 23:9; Dt 10:18–19)