They made a calf in Horeb
A golden one, of the earrings of gold which were in the ears of their wives, sons, and daughters; these they took and melted down, and cast into the figure of a calf, or an ox, as it is afterwards said, in imitation of the Egyptians, who worshipped the ox; a people that had used them ill, from whose bondage they were just delivered; on whom they had seen the judgments of God inflicted, and who were notoriously wicked and an idolatrous people, and yet these they imitated; and, which was still a greater aggravation, this they did in Horeb, the mountain in which God appeared in so terrible a manner, with thunder and lightnings, and in fire, out of which he spoke to them; and when he gave them a body of laws, among which were one that forbid the worshipping of graven images; and yet they made and worshipped one in this very place, from whence they received this law; as follows.
And worshipped the molten image;
when fashioned with a graving tool, and made a molten calf, they said, these be thy gods, O Israel, which brought thee out of Egypt; and they brought their burnt offerings and peace offerings, and ate and drank before it, and danced about it; all which were acts of idolatrous worship, ( Exodus 32:1-6 ) ( 1 Corinthians 10:7 ) . This was so heinous a sin, that the Jews say it is not expiated to this day, and that there is no punishment comes upon them but there is an ounce of the golden calf in it F17.
F17 T. Hieros. Taanioth, fol. 80. 4.