Judges 21:18

Howbeit, we may not give them wives of our daughters
Though their case was so very necessitous and desperate:

for the children of Israel have sworn, saying, cursed be he that giveth
a wife to Benjamin,
( Judges 21:1 ) and therefore without the violation of their oath could not give any of their daughters in marriage to them: wherefore some other way must be devised to help them.