1 Samuel 19:4-6

Then Jonathan spoke well of David to Saul his father and said to him, “Do not let the king sin against his servant David, since he has not sinned against you, and since his deeds have been very beneficial to you. For he took his life in his hand and struck the Philistine, and the LORD brought about a great deliverance for all Israel; you saw it and rejoiced. Why then will you sin against innocent blood by putting David to death without a cause?” Saul listened to the voice of Jonathan, and Saul vowed, “As the LORD lives, he shall not be put to death.”