John Gill Bible Commentary

Behold, he smote the rock, that the waters gushed out, and the streams overflowed,.... This they allow was done by him, for these are their words continued; suggesting, that though the waters did gush out upon smiting the rock, yet they might have been in the caverns of it before, and had remained there a long time, and might have come out of themselves; and therefore this was no such great matter, and might easily be accounted for: but can he give bread also? solid, substantial bread, and not like this light bread, the manna, as they called it, Num 21:5, can he give us bread of corn, in a wilderness which is not a place of seed, where no corn grows? can he do this? this would show his power indeed: can he provide flesh for his people? for so great a multitude, and in a place where no cattle are? let him do this, and we will believe his power; or else the words intimate that the smiting of the rock, and the waters flowing in such large streams, were an instance of his power, and therefore he that could do the one could do the other; he that could bring such large quantities of water out of a rock could give them solid bread and suitable flesh, and fulness of both; and should he not do so, they must conclude that he bore no good will to them, and had no love and kindness for them.