Exodus 4:24-26

24 On the way, at a place where they spent the night, the Lord met him and tried to kill him.
25 But Zipporah took a flint and cut off her son's foreskin, and touched Moses' feet with it, and said, "Truly you are a bridegroom of blood to me!"
26 So he let him alone. It was then she said, "A bridegroom of blood by circumcision."