'King of Israel' in the Bible

After whom hath the king of Israel come out? after whom art thou pursuing? -- after a dead dog! after one flea!

And now, let not my blood fall to the earth over-against the face of Jehovah, for the king of Israel hath come out to seek one flea, as one pursueth the partridge in mountains.'

And the heads of the Philistines say, 'What are these Hebrews?' and Achish saith unto the heads of the Philistines, 'Is not this David servant of Saul king of Israel, who hath been with me these days or these years, and I have not found in him anything wrong from the day of his falling away till this day.'