John Calvin Commentary Psalms 78:19

"Yea, they spake against God; They said, Can God prepare a table in the wilderness?" — Psalms 78:19 (ASV)

And they spoke against God. The prophet had said that they tempted God in their heart; and now he adds, that they were not ashamed openly to utter with their impure and blasphemous tongues, the impiety which they had inwardly conceived. From this, it is all the more clear that malignity and wickedness had taken entire possession of their hearts.

Thus we see how lust conceives sin, when it is admitted into the soul with unholy consent. Afterwards the sin develops further, even as we see the Israelites proceeding to such a length of profane indulgence, as to call in question the power of God, as if they took no account of it, any further than as it catered to their lust. By the table prepared which is spoken of, is to be understood the fine food, which was their usual food in Egypt. A single dish did not satisfy their appetite. They were not content unless they could gratify themselves with great abundance and variety. When it is said in the following verse, Behold! God smote the rock, and the waters gushed out, etc., this, I have no doubt, is the language of bitter irony, with which the prophet taunts their unblushing insolence. It is not very likely that they spoke in this manner; but he relates, as it were, in their own voice, or adopting their persona, the things which took place before their eyes.