Exodus 4:24-26

It happened on the way at a lodging place, that Yahweh met him and wanted to kill him.

Then Zipporah took a flint, and cut off the foreskin of her son, and cast it at his feet; and she said, "Surely you are a bridegroom of blood to me."

So he let him alone. Then she said, "You are a bridegroom of blood," because of the circumcision.