'Swear' in the Bible

“You provided bread from heaven for them for their hunger,You brought forth water from a rock for them for their thirst,And You told them to enter in order to possessThe land which You swore to give them.

So I contended with them and cursed them and struck some of them and pulled out their hair, and made them swear by God, “You shall not give your daughters to their sons, nor take of their daughters for your sons or for yourselves.