Exodus 32:26-33

then Moses stood in the gate of the camp and said, “Who is on the LORD’s side? Come to me.” And all the sons of Levi gathered around him. And he said to them, “Thus says the LORD God of Israel, ‘Put your sword on your side each of you, and go to and fro from gate to gate throughout the camp, and each of you kill his brother and his companion and his neighbor.’” And the sons of Levi did according to the word of Moses. And that day about three thousand men of the people fell. And Moses said, “Today you have been ordained for the service of the LORD, each one at the cost of his son and of his brother, so that he might bestow a blessing upon you this day.” The next day Moses said to the people, “You have sinned a great sin. And now I will go up to the LORD; perhaps I can make atonement for your sin.” So Moses returned to the LORD and said, “Alas, this people has sinned a great sin. They have made for themselves gods of gold. But now, if you will forgive their sin—but if not, please blot me out of your book that you have written.” But the LORD said to Moses, “Whoever has sinned against me, I will blot out of my book.