Psalms 78:21,22 - Joseph Benson’s Commentary on the Old and New Testaments

The Lord heard, and was wroth Such rude and insolent language highly incensed the Divine Majesty. So a fire was kindled against Jacob He sent lightning from heaven to consume those whom he had before cherished, Numbers 11:1. Or, the expression may be taken figuratively for the fire of God's anger, as it follows. Observe, reader, God is a witness to all our murmurings and distrusts: he hears them, and is much displeased with them. To unbelievers our God is himself a consuming fire, and those that will not confide in the power of his mercy shall feel the power of his indignation, and be made to confess that it is a fearful thing to fall into his hands. Because they believed not in God Because, by this their distrust and murmuring, it appeared that they did not give credit to the revelation God had made of himself to them: for they durst not commit themselves to his care, nor venture themselves in his hands; and trusted not in his salvation That he could and would save them from the famine and destruction which they feared; they trusted not in the salvation he had begun to work for them; for, if they had, they would not thus have questioned its progress. Mark well, reader, those cannot be said to trust in God's salvation as their felicity at last, who cannot find in their hearts to trust in his providence for food convenient in the way to it.