Judges 21:7

How shall we do for wives for them that remain
By which it seems, as well as by what is after related, that they knew of the six hundred men hid in the rock Rimmon:

seeing we have sworn by the Lord;
by the Word of the Lord, as the Targum; and such an oath with them was a sacred thing, and to be kept inviolable, even to their own hurt:

that we will not give them of our daughters to wives;
as in ( Judges 21:1 ) and therefore they must either marry among the Heathens, which was forbidden, or they must make void their oath, or the tribe in a little time would be extinct; these were difficulties they knew not how to surmount, and this was the object of their inquiry.