'Swear by God' in the Bible

And he also rebelled against king Nebuchadnezzar, who had made him swear by God: but he stiffened his neck, and hardened his heart against turning unto the LORD God of Israel.

And I contended with them, and pronounced them cursed, and struck certain of them, and plucked off their hair, and made them swear by God, saying, You shall not give your daughters unto their sons, nor take their daughters unto your sons, or for yourselves.