1 Samuel 25:22

So and more also do God unto the enemies of David, if I leave of all that pertain to him by the morning light any that pisseth against the wall.

So and more also do God unto the enemies of David. In making this vow utterly to destroy Nabal's house, David committed sin. The fulfillment of it by the execution of his vindictive threat was clearly opposed to the will of God.