He telleth the number of the stars - He counts them all. God only can do this. The stars are so numerous that no astronomer can count them; they lie so far in the depths of space, and are so remote from each other, that no man can be so presumptuous as to suppose that he has even seen any considerable part of them, even by the aid of the most powerful telescopes.
He calleth them all by their names - As if each one had a name, and God could call them forth one by one by their names, like the muster-roll of an army. This language seems to be taken from Isaiah 40:26 : “Lift up your eyes on high, and behold who hath created these things, that bringeth out their host by numbers; he calleth them all by names, by the greatness of his might, for that he is strong in power; not one faileth.” See the notes at that passage.