Mormon stresses that Yahweh had instructed him to resign from the army’s leadership. In verse 11 he reported the same decision as though it were his own. We cannot know when Yahweh justified his action, but Mormon is indicating that it was in accord with Yahweh’s will. Yahweh’s “vengeance” was the law of the harvest: allowing the Nephites to dash themselves against their own pride. God need not wreak vengeance upon us. We are perfectly capable of wreaking it upon ourselves.