Charles H. Spurgeon on Psalms 78:21

Therefore the Lord heard this, and was wroth. He was not indifferent to what they said. He dwelt among them in the holy place, and, therefore, they insulted him to his face. He did not hear a report of it, but the language itself came into his ears. So a fire was kindled against Jacob. The fire of his anger which was also attended with literal burnings. And anger also came up against Israel. Whether he viewed them in the lower or higher light, as Jacob or as Israel, he was angry with them: even as mere men they ought to have believed him; and as chosen tribes, their wicked unbelief was without excuse. The Lord doeth well to be angry at so ungrateful, gratuitous and dastardly an insult as the questioning of his power.