John Calvin Commentary Psalms 78:21

"Therefore Jehovah heard, and was wroth; And a fire was kindled against Jacob, And anger also went up against Israel;" — Psalms 78:21 (ASV)

Therefore Jehovah heard, and was wroth. This hearing of God implies full and perfect knowledge, and it is a figure taken from earthly judges, who cannot punish criminals until they are thoroughly acquainted with the case. He is said to hear His own people when He shows His favor and mercy towards them by granting their requests; and, on the other hand, He is said to hear those blasphemies which He does not allow to pass unpunished.

To remove all ground for thinking that the divine wrath was unduly severe, the enormity of the Israelites' guilt is again described as manifested in this: they believed not God, nor trusted in his salvation. It is taken here as an indisputable point that promises were made to them, to which they ought to have given their assent. However, they were prevented from doing so by the extreme infatuation with which they were carried away.

To trust in the salvation of God, is to lean upon His fatherly providence and to regard Him as sufficient for the supply of all our wants. From this we learn not only how hateful unbelief is in the sight of God, but also what the true nature of faith is, and what fruits it produces.

Why is it that men quietly submit themselves to Him, if not because they are persuaded that their salvation is singularly precious in His sight and are fully assured that He will give them whatever they need? Thus they are led to surrender themselves to Him, to be governed according to His good pleasure.

Faith, then, is the root of true piety. It teaches us to hope for and desire every blessing from God, and it forms us to yield obedience to Him; while those who distrust Him must necessarily always be murmuring and rebelling against Him. The scope of the prophet is this: that the pretenses of faith made by those who do not hope for salvation from God rest on false grounds; for when God is believed in, the hope of salvation is quickly produced in the mind, and this hope renders to Him praise for every blessing.