The teaching of the wise is a fountain of life, that one may avoid the snares of death. Proverbs 13:14
The fear of Yahweh is a fountain of life, that one may avoid the snares of death. Proverbs 14:2762
These two sayings show that the "fear of Yahweh" and the "teaching of the wise" are interchangeable. Both hold open the promise of life. If Yahweh is indeed this kind of God, and the "teaching of the wise" is life-securing, then it is wholly consistent for Proverbs to counsel against taking vengeance. Who needs to engage in such behavior characteristic of (self-destructive) enemies? Rather, one should "wait for Yahweh, and he will help you" (20:22).
This trust in Yahweh also underlies the single explicit instruction to aid the enemy in his need (25:21-22). In addition to the repentance effected in the enemy, Yahweh himself may be counted upon to complete such behavior. This instruction, far from being "marred by the last line,"64 expresses an abiding faith in Yahweh's life-securing activity on behalf of those who do good to those who hate them. In spite of the well-known inscrutability--even danger--of Yahweh, Proverbs maintains that he can be trusted.
Cf. 11:9; 14:25.
0esterley, p. 229.