Moses
Numbers 21:5ESV·traditional attribution

And the people spoke against God and against Moses, “Why have you brought us up out of Egypt to die in the wilderness? For there is no food and no water, and we loathe this worthless food.”

John Calvin Reformed @genevareformer

5. And the people spake against God and against Moses. Either because they murmured against God in the person of Moses, or else because their impiety broke forth to such a furious extent, that they openly blasphemed against God; and this latter opinion is most in accordance with the words, because by their use of the plural number they accuse two parties together.

Matthew Henry Presbyterian @wholebiblehenry

Here is, I. The fatigue of Israel by a long march round the land of Edom, because they could not obtain passage through it the nearest way: The soul of the people was much discouraged because of the way, Num 21:4.

Commenting on Numbers 21:4-9

John Gill Reformed Baptist @doctorgill

And the people spake against God,.... Who went before them in the pillar of cloud and fire, for leading them in such a way; that is, against Christ, as the apostle has taught us to interpret it, Co1 10:9, and is no inconsiderable proof of the deity of Christ; and so the Targum of Jonathan paraphrases it,"and the people thought in their heart, and spake...