1 Samuel 18:19 (KJV)

And Saul said to David, Behold my elder daughter Merab, her will I give thee to wife: only be thou valiant for me, and fight the Lord’s battles. For Saul said, Let not mine hand be upon him, but let the hand of the Philistines be upon him.

And David said unto Saul, Who am I? and what is my life, or my father’s family in Israel, that I should be son in law to the king?

But it came to pass at the time when Merab Saul’s daughter should have been given to David, that she was given unto Adriel the Meholathite to wife.

And Michal Saul’s daughter loved David: and they told Saul, and the thing pleased him.

And Saul said, I will give him her, that she may be a snare to him, and that the hand of the Philistines may be against him. Wherefore Saul said to David, Thou shalt this day be my son in law in the one of the twain.