Exodus 32:26-33

then Moses stood in the gate of the camp, and said, Whoso is on Jehovah’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 Jehovah, the God of Israel, Put ye every man his sword upon his thigh, and go to and fro from gate to gate throughout the camp, and slay every man his brother, and every man his companion, and every man his neighbor. And the sons of Levi did according to the word of Moses: and there fell of the people that day about three thousand men. And Moses said, Consecrate yourselves to-day to Jehovah, yea, every man against his son, and against his brother; that he may bestow upon you a blessing this day. And it came to pass on the morrow, that Moses said unto the people, Ye have sinned a great sin: and now I will go up unto Jehovah; peradventure I shall make atonement for your sin. And Moses returned unto Jehovah, and said, Oh, this people have sinned a great sin, and have made them gods of gold. Yet now, if thou wilt forgive their sin—; and if not, blot me, I pray thee, out of thy book which thou hast written. And Jehovah said unto Moses, Whosoever hath sinned against me, him will I blot out of my book.