John Calvin Commentary Numbers 23:9

"For from the top of the rocks I see him, And from the hills I behold him: lo, it is a people that dwelleth alone, And shall not be reckoned among the nations." — Numbers 23:9 (ASV)

For from the top of the rocks I see him. Unless I am mistaken, the meaning is that although he only saw the people from a distance, so that he could not accurately perceive their power from such a high and distant spot, they still indicated to him something great and formidable. A closer view generally intimidates people; besides, a body of twenty thousand men then dazzles our sight, as if the number were five times as great, while the real extent of a thing is also more accurately determined. But Balaam declares, in the spirit of prophecy, that he sees far more in the people of God than their distance from him would allow; for, positioned as he was on a high eminence, he would have only beheld them as dwarfs with the ordinary vision of men.

He says that the people shall dwell alone, as being not at all in need of external support: for לבדד, lebadad, is equivalent to solitarily or separately. It is said of the people, therefore, that they shall dwell in such a manner as to be content with their own condition, neither desiring the wealth or power of others, nor seeking their aid. The fact that the people resorted at one time to the Egyptians, at another to the Assyrians, and entangled themselves in improper alliances, is not contrary to this prophecy, in which the question is not about the virtue of the people, but only about the blessing of God, which is again celebrated in the same words in Deuteronomy 33:28.

What follows, that they shall not be reckoned among the nations, must not be understood as devaluing them, as if it were said that they should be of no credit or position. Instead, the elect people are exalted above all others in dignity and excellence, as if he had said that there would be no nation under heaven equal to or comparable with them. And, although there were other kingdoms more illustrious for the flourishing condition of their people, and superior both in the number of their inhabitants and in all kinds of prosperity, still this people never forfeited their pre-eminence, since they were distinguished not so much by wealth and external endowments as by the adoption of God. Thus, Mount Sion is called noble above all other mountains, because God had chosen to make His abode there.

Others explain it that the people should be alone, so as not to be brought into comparison with the Gentiles, since its religion should be separate from the whole world and unmingled with heathen corruptions. The exposition which I have given is, however, more simple.