Saul said to David, Behold, my elder daughter Merab, her will I give you as wife: only be valiant for me, and fight Yahweh's battles. For Saul said, Don't let my hand be on him, but let the hand of the Philistines be on him.
David, unable to provide a proper gift to Saul for Merab, would have another opportunity to become the king's son-in-law; and the cunning and crafty Saul must have thought, "This time, I'll get him killed for sure." It came about when Saul learned that his daughter Michal had fallen in love with David.