How do we know that David's actions were justifiable?

David's actions in sparing Saul can be justified through his reasoning that the Lord's anointed should not be harmed. In 1 Samuel 26:11, David asserts, 'The Lord forbid that I should stretch forth mine hand against the Lord's anointed.' This indicates that David understood the gravity of killing the king, whom God appointed. He showed great moral conviction, believing that it was wrong to act outside God's will, demonstrating a faith that relies on God's timing and justice to rectify the situation.