Charles H. Spurgeon on Psalms 106:21

They forgat God their saviour. Remembering the calf involved forgetting God. He had commanded them to make no image, and in daring to disobey they forgot his commands. Moreover, it is clear that they must altogether have forgotten the nature and character of Jehovah, or they could never have likened him to a grass eating animal. Some men hope to keep their sins and their God too —the fact being that he who sins is already so far departed from the Lord that he has actually forgotten him. Which had done great things in Egypt. God in Egypt had overcome all the idols, and yet they so far forgot him as to liken him to them. Could an ox work miracles? Could a golden calf cast plagues upon Israel's enemies? They were brutish to set up such a wretched mockery of deity, after having seen what the true God could really achieve. "Wondrous works in the land of Ham, and terrible things by the Red sea". They saw several ranges of miracles, the Lord did not stint them as to the evidences of his eternal power and godhead, and yet they could not rest content with worshipping him in his own appointed way, but must needs have a Directory of their own invention, an elaborate ritual after the old Egyptian fashion, and a manifest object of worship to assist them in adoring Jehovah. This was enough to provoke the Lord, and it did so; how much he is angered every day in our own land no tongue can tell.