The thing pleased him Not out of any love to David, or desire to perform his promise; but because he hoped, by her means, to bring his ends about of destroying David. That she may be a snare to him He hoped his daughter, in obedience to him, might be persuaded to bring him into some snare that he would lay for him: or that, being exposed to great dangers, (which he was to undergo, as a condition of having her to wife,) he might perish in some of them. Thou shalt be this day my son-in- law That is, shortly, within a little time. In the one of the twain Saul seems in this to have told David that though some reasons of state had obliged him to give his elder daughter to Adriel, yet still he would have him for his son-in-law, by giving the other unto him.
Related Commentaries of 1 Samuel 18:20
1 Samuel 18:20-21
20 And Michal Saul's daughter loved David: and they told Saul, and the thing pleased him.d
21 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.