And Moses returned unto the LORD, and said, Oh, this people have sinned a great sin, and have made them gods of gold.

Wesley's Notes

32:31 Oh, this people have sinned a great sin - God had first told him of it, Ex 32:7, and now he tells God of it by way of lamentation. He doth not call them God's people, he knew they were unworthy to be called so, but this people. This treacherous ungrateful people, they have made them gods of gold.

Matthew Henry's Concise Commentary

32:30-35 Moses calls it a great sin. The work of ministers is to show people the greatness of their sins. The great evil of sin appears in the price of pardon. Moses pleads with God for mercy; he came not to make excuses, but to make atonement. We are not to suppose that Moses means that he would be willing to perish for ever, for the people's sake. We are to love our neighbour as ourselves, and not more than ourselves. But having that mind which was in Christ, he was willing to lay down his life in the most painful manner, if he might thereby preserve the people. Moses could not wholly turn away the wrath of God; which shows that the law of Moses was not able to reconcile men to God, and to perfect our peace with him. In Christ alone, God so pardons sin as to remember it no more. From this history we see, that no unhumbled, carnal heart, can long endure the holy precepts, the humbling truths, and the spiritual worship of God. But a god, a priest, a worship, a doctrine, and a sacrifice, suited to the carnal mind, will ever meet with abundance of worshippers. The very gospel itself may be so perverted as to suit a worldly taste. Well is it for us, that the Prophet like unto Moses, but who is beyond compare more powerful and merciful, has made atonement for our souls, and now intercedes in our behalf. Let us rejoice in his grace.