Exodus 4:24-26

At a lodging place on the way, the LORD met Moses and was about to kill him. But Zipporah took a flint knife, cut off her son’s foreskin and touched Moses’ feet with it. “Surely you are a bridegroom of blood to me,” she said. So the LORD let him alone. (At that time she said “bridegroom of blood,” referring to circumcision.)