2 Samuel 3:13

I will make a league with thee, to wit, upon thy terms; which, all circumstances considered, seems to be lawful, to prevent the great effusion of Israelitish blood, which otherwise would certainly have been split. And although the principle of this action of Abner's was base and wicked, yet the action itself was lawful and commendable, and no more than his duty to God and David obliged him to; and therefore David might well persuade and induce him to it.