ISB ~ 2 John 1 v5

from the beginning:John’s teaching about love is not new but is traceable back to the initial catechesis of his readers (6; 1 Jn 3:11).

love one another:The supreme mandate that Christ has laid upon his disciples (Jn 13:34). The meaning of his words is explained by his example, which shows us that Christian love is not an emotion, but an act of the will that adheres to the commandments of God (Jn 14:31) and expresses itself through heroic generosity and sacrifice, even to the point of death (Jn 15:13).