1 Samuel 19:4-8

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.

And Jonathan called David, and Jonathan shewed him all those things. And Jonathan brought David to Saul, and he was in his presence, as in times past.

And there was war again: and David went out, and fought with the Philistines, and slew them with a great slaughter; and they fled from him.