'King of Israel' in the Bible

After whom has the king of Israel come out? Whom are you pursuing? A dead dog, a single flea?

Now then, do not let my blood fall to the ground away from the presence of the Lord; for the king of Israel has come out to search for a single flea, just as one hunts a partridge in the mountains.”

Then the commanders of the Philistines said, “What are these Hebrews doing here?” And Achish said to the commanders of the Philistines, “Is this not David, the servant of Saul the king of Israel, who has been with me these days, or rather these years, and I have found no fault in him from the day he deserted to me to this day?”