John Gill's Bible Commentary Ver. 6. And Saul hearkened unto the voice of Jonathan , etc.] Not only heard him out what he had to say, but was affected with it, and wrought upon by it, and was convicted for the present that he was wrong in seeking the life of David, and therefore would desist from it; the Lord working upon his mind by what Jonathan said, and inclined him to listen to it, and act accordingly: and Saul sware, [as] the Lord liveth, he shall not be slain ; this oath he added to what he said to Jonathan, for the confirmation of it; and which was taken either with a real intention to keep it, though that intention did not long continue; or with a view to deceive Jonathan, that he might acquaint David with it, and so prevent his flight and escape, and that he might the more easily fall into his hands; but the former seems rather to be the case.
Matthew Henry Commentary
Verses 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 malic against David. So incurable is the hatred of the seed of the serpen against that of the woman; so deceitful and desperately wicked is the heart of man without the grace of God, Jer 17:9.
Original Hebrew וישׁמע8085 שׁאול7586 בקול6963 יהונתן3083 וישׁבע7650 שׁאול7586 חי2416 יהוה3068 אם518 יומת׃4191