And when the people saw that Moses delayed to come down out of the mount, the people gathered themselves together unto Aaron, and said unto him, Up, 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 Aaron said unto them, Break off the golden earrings, which are in the ears of your wives, of your sons, and of your daughters, and bring them unto me.
And all the people brake off the golden earrings which were in their ears, and brought them unto Aaron.
And he received them at their hand, and fashioned it with a graving tool, after he had made it a molten calf: and they said, These be thy gods, O Israel, which brought thee up out of the land of Egypt.
And when Aaron saw it, he built an altar before it; and Aaron made proclamation, and said, To morrow is a feast to the Lord.
And they rose up early on the morrow, and offered burnt offerings, and brought peace offerings; and the people sat down to eat and to drink, and rose up to play.
Exodus 32:21-29 (KJV)
And Moses said unto Aaron, What did this people unto thee, that thou hast brought so great a sin upon them?
And Aaron said, Let not the anger of my lord wax hot: thou knowest the people, that they are set on mischief.
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.
For Moses had said, Consecrate yourselves today to the Lord, even every man upon his son, and upon his brother; that he may bestow upon you a blessing this day.