John Calvin Commentary Deuteronomy 9:20

"And Jehovah was very angry with Aaron to destroy him: and I prayed for Aaron also at the same time." — Deuteronomy 9:20 (ASV)

And the Lord was very angry with Aaron. From this it appears how futile are the excuses by which people try to conceal their faults, until a genuine fear of God compels them to acknowledge their guilt. Although Aaron did not claim to be entirely innocent, he still tried to erase, or at least lessen, the enormity of his crime by claiming he acted under compulsion. But Moses declares that God was very angry with him. From this it follows that he was guilty of a very serious sin, which is also more certainly confirmed by the severity of his punishment; for God would never have been so moved as to destroy him, unless he had been worthy of this condemnation.

In the next verse, the word sin is not applied to the act itself,³⁹² but is transferred by metonymy to the calf, as its apposition shows. Again, by stating that he had thoroughly broken the calf to pieces by grinding it until it was reduced to powder, he signifies once more how abominable this idol was, especially when he adds that the powder was thrown into the stream, so that no memorial of it would continue to exist.

³⁹² “Il appelle le veau Peche du peuple, pource qu’il avoit este la matiere et object de leur idolatrie;” he calls the calf the Sin of the people, because it had been the matter and object of their idolatry. — pource qu’il avoit este la matiere et object de leur idolatrie;” he calls the calf the Sin of the people, because it had been the matter and object of their idolatry. — Fr.