1 Samuel 19:4-6

And Jonathan spake good of David unto Saul his father, and said unto him, Let not the king sin against his servant, against David; because he hath not sinned against thee, and because his works have been to thee-ward very good: for he did put his life in his hand, and slew the Philistine, and the LORD wrought a great salvation for all Israel: thou sawest it, and didst rejoice: wherefore then wilt thou sin against innocent blood, to slay David without a cause? And Saul hearkened unto the voice of Jonathan: and Saul sware, As the LORD liveth, he shall not be slain.