John Calvin Commentary Numbers 14:5

"Then Moses and Aaron fell on their faces before all the assembly of the congregation of the children of Israel." — Numbers 14:5 (ASV)

Then Moses and Aaron fell on their faces. It is doubtful whether they humbled themselves so much toward the people as to be prostrate before them, or whether it was in prayer that they fell with their faces to the earth. The latter, however, seems more likely to me, as if, by turning to God in this way, they reproved the stupidity of the people.

Indeed, in such a case of obduracy, nothing remained except to call upon God, yet so that the prayer should be made in the sight of all, in order to influence their minds.

Otherwise, they might have sought some place of seclusion; but by this pitiful spectacle, they endeavored to recall the people to their right senses.

This, indeed, is beyond dispute: they sought nothing on their own behalf but were only anxious for the welfare of the people. For if the people had gone back, Moses and Aaron would have been free to sojourn in the land of Canaan or elsewhere.

Yet they were not merely concerned about the people; rather, the interruption of God’s grace troubled them most, for with it the Covenant made with Abraham would also have been buried.

In short, they justly felt this to be the same as if they had seen both the glory of God and the salvation of the human race altogether brought to nothing.

Therefore, those who were unmoved by this sad sight must indeed have been more than senseless, especially when Moses, whom God had exalted by so many privileges above all other mortals, was lying prostrate on the earth for their sake.