'Swear' in the Bible

“Again, you have heard that it was said to the men of old, ‘You shall not make false vows, but you shall fulfill your vows to the Lord [as a religious duty].’

Nor shall you make an oath by your head, for you are not able to make a single hair white or black.

But Jesus kept silent. And the high priest said to Him, “I call on You to swear a binding oath by the living God, that you tell us whether You are the Christ, the Son of God.”

Then he began to curse [that is, to invoke God’s judgment on himself] and swear [an oath], “I do not know the man!” And at that moment a rooster crowed.