'King of Israel' in the Bible

After whom art thou come out, thou king of Israel? After whom chasest thou? Even after a dead dog, and after a flea!

And yet I hope my blood shall not fall to the earth before the face of the LORD, though the king of Israel be come out to hunt a flea, as men hunt the partridges in the mountains."

Then said the lords of the Philistines, "What are yonder Hebrews?" And Achish said unto the lords of the Philistines, "Is not this David the servant of Saul the king of Israel, which hath been with me days or years? And I have found no fault in him since he fled unto me unto this day."