'King of Israel' in the Bible

After whom, hath the king of Israel come forth? After whom, art thou in pursuit? After a dead dog! after a single flea!

Now, therefore, let not my blood fall to the earth, away from the presence of Yahweh, - for the king of Israel hath come out to hunt for a single flea, as when one pursueth a partridge among the mountains.

Then said the princes of the Philistines, What are these Hebrews doing ? And Achish said unto the princes of the Philistines - Is not this David, servant of Saul king of Israel, who hath been with me this year, or two, and I have found in him nothing, from the day of his coming over unto me unto this day?