▼4:24It seems, from the context of the story, that the one the Lord was willing to kill was not Moses, but the firstborn son of Moses. The prior verse spoke about firstborn sons, so the editor placed this event immediately after that text.(Conte)

▼4:24 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)