In the one of the twain - Some prefer “the second time” Job 33:14. The first contract had been broken by giving Merab to Adriel.
Related Commentaries of 1 Samuel 18:21
1 Samuel 18:21
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.