4 And Jonathan spoke well of David to Saul his father and said to him, "Let not the king sin against his servant David, because he has not sinned against you, and because his deeds have brought good to you. 5 For he took his life in his hand and he struck down the Philistine, and the Lord worked a great salvation for all Israel. You saw it, and rejoiced. Why then will you sin against innocent blood by killing David without cause?" 6 And Saul listened to the voice of Jonathan. Saul swore, "As the Lord lives, he shall not be put to death."
Matthew Henry's Commentary on 1 Samuel 19:4-6
Commentary on 1 Samuel 19:1-10
(Read 1 Samuel 19:1-10)
How forcible are right words! Saul was, for a time, convinced of the unreasonableness of his enmity to David; but he continued his malice against David. So incurable is the hatred of the seed of the serpent against that of the woman; so deceitful and desperately wicked is the heart of man without the grace of God, Jeremiah 17:9.