Exodus 4:24

Verse 24. The Lord met him, and would have killed him. This was an angel representing the Lord, who treated Moses in this manner, for having neglected the circumcision of his younger son: which his wife understanding, circumcised her child upon the spot, upon which the angel let Moses go. Challoner.—Both his children were born about this time. But Eliezer, the younger, had not been circumcised; and therefore remained under the power of the destroying angel. Orig. c. Cels. v. Others think the angel was going to kill Moses. Calmet.