Exodus 32:28-32

And the children of Levi did according to the word of Moses: and there fell of the people that day about three thousand men.

For Moses had said, Consecrate yourselves to day to the LORD, even every man upon his son, and upon 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 the LORD; peradventure I shall make an atonement for your sin.

And Moses returned unto the LORD, 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.