Then Saul said to David, “Here is my elder daughter Merab. I will give her to you for a wife. Only be valiant for me and fight the LORD’s battles.” For Saul thought, “Let not my hand be against him, but let the hand of the Philistines be against him.”
Saul feared David because he sensed that God had left him and was with David instead. Note this well: those truly great and to be reverenced have God with them. David's wise behavior only deepened Saul's fear, for wisdom commands respect where threats and hectoring earn only the contempt of the discerning. Saul foolishly removed him from court, thinking to weaken him, but gave David instead a chance to win the people's love.
AI summary
Commenting on 1 Samuel 18:12-30
And David said unto Saul,.... Surprised at the offer Saul made him, yet not refusing it, but expressing himself with great modesty and humility: who am I? as to his person, parentage, and employment, mean and despicable, at least in his own eyes, a type of the lowly Jesus, Mat 11:29, and what is my life?
HE OFFERS HIM HIS DAUGHTER FOR A SNARE. (Sa1 18:17-21) Saul said to David, Behold my elder daughter Merab, her will I give thee to wife--Though bound to this already [Sa1 17:25], he had found it convenient to forget his former promise. He now holds it out as a new offer, which would tempt David to give additional proofs of his valor.