'King of Israel' in the Bible

After whom is the king of Israel come out? After whom do thou pursue? After a dead dog, after a flea.

Now therefore, let not my blood fall to the earth away from the presence of LORD. For the king of Israel has come out to seek a flea, as when [a man] hunts a partridge in the mountains.

Then the rulers of the Philistines said, What [are] these Hebrews? And Achish said to the rulers of the Philistines, Is not this David, the servant of Saul the king of Israel, who has been with me these days, or [rather] these year