There’s no indication David knows anything about this unnamed servant who intervenes. The Lord may have kept us from temptation and sin in ways we know nothing about. David is saved from sin through the actions of a saviour, Abigail. She comes with humility and owns Nabal’s guilt, as Christ is willing to own our guilt. He takes the punishment for us so that justice is done. Abigail reminds David that he is going to be king; a consideration of our destination will keep us from sin.