Exodus 32:26-33

So he stood at the entrance to the camp and said, ‘Whoever is for the LORD, come to me.’ And all the Levites rallied to him. Then he said to them, ‘This is what the LORD, the God of Israel, says: “Each man strap a sword to his side. Go to and fro through the camp from one end to the other, each killing his brother and friend and neighbour.” ’ The Levites did as Moses commanded, and that day about three thousand of the people died. Then Moses said, ‘You have been set apart to the LORD today, for you were against your own sons and brothers, and he has blessed you this day.’ The next day Moses said to the people, ‘You have committed a great sin. But now I will go up to the LORD; perhaps I can make atonement for your sin.’ So Moses went back to the LORD and said, ‘Oh, what a great sin these people have committed! They have made themselves gods of gold. But now, please forgive their sin – but if not, then blot me out of the book you have written.’ The LORD replied to Moses, ‘Whoever has sinned against me I will blot out of my book.