Exodus 32:23-28

For they said unto me, Make us gods, which shall go before us: for as for this Moses, the man that brought us up out of the land of Egypt, we wot not what is become of him. And I said unto them, Whosoever hath any gold, let them break it off. So they gave it me: then I cast it into the fire, and there came out this calf. And when Moses saw that the people were naked; (for Aaron had made them naked unto their shame among their enemies:) then Moses stood in the gate of the camp, and said, Who is on the LORD's side? let him come unto me. And all the sons of Levi gathered themselves together unto him. And he said unto them, Thus saith the LORD God of Israel, Put every man his sword by his side, and go in and out from gate to gate throughout the camp, and slay every man his brother, and every man his companion, and every man his neighbour. And the children of Levi did according to the word of Moses: and there fell of the people that day about three thousand men.