1 Samuel 18:20

18And 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?

19But 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.

20And Michal Saul’s daughter loved David: and they told Saul, and the thing pleased him.

21And 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.

22And Saul commanded his servants, saying, Commune with David secretly, and say, Behold, the king hath delight in thee, and all his servants love thee: now therefore be the king’s son in law.