In Gibeah of Saul, whom the Lord did choose— Whom the Lord had chosen, says Houbigant; or, according to the word of the Lord: for when David asks the Gibeonites, 2 Samuel 21:3. What shall I do for you? it seems, God had commanded that the wickedness of Saul should be expiated with that blood which the Gibeonites should require; otherwise David would have consulted God only, and would not have gone to the Gibeonites to inquire of them what they would choose.
Related Commentaries of 2 Samuel 21:6
2 Samuel 21:6
6 Let seven men of his sons be delivered unto us, and we will hang them up unto the LORD in Gibeah of Saul, whom the LORD did choose. And the king said, I will give them.