John Calvin Commentary Numbers 21:5

"And the people spake against God, and against Moses, Wherefore have ye brought us up out of Egypt to die in the wilderness? for there is no bread, and there is no water; and our soul loatheth this light bread." — Numbers 21:5 (ASV)

And the people spoke against God and against Moses. Either because they murmured against God in the person of Moses, or because their impiety erupted to such a furious extent that they openly blasphemed against God. This latter opinion is most consistent with the words, because by their use of the plural number they accuse two parties together.¹²⁰

But since Moses had nothing separate from God, no one could contend with him without also warring against God Himself. Here, however, as I have said, their insolence went even further, so that they not only railed against the minister but also vomited forth their wicked blasphemy against God Himself, as if He had gravely injured them by their deliverance.

¹²⁰ Addition in Fr., “sinon qu’ils s’addressent aussi a Aaron;” unless they also address Aaron. “sinon qu’ils s’addressent aussi a Aaron;” unless they also address Aaron.