Exodus 4:24-26

At a lodging place on the way the LORD met him and sought to put him to death. Then Zipporah took a flint and cut off her son’s foreskin and touched Moses’ feet with it and said, “Surely you are a bridegroom of blood to me!” So he let him alone. It was then that she said, “A bridegroom of blood,” because of the circumcision.