Book of Exodus

²³ And I say unto thee, Let my son go, that he may serve me: and if thou refuse to let him go, behold, I will slay thy son, even thy firstborn.
²⁴ And it came to pass by the way in the inn, that the LORD met him, and sought to kill him.
²⁵ Then Zipporah took a sharp stone, and cut off the foreskin of her son, and cast it at his feet, and said, Surely a bloody husband art thou to me.
²⁶ So he let him go: then she said, A bloody husband thou art, because of the circumcision.