Albert Barnes Commentary Isaiah 26:15

"Thou hast increased the nation, O Jehovah, thou hast increased the nation; thou art glorified; thou hast enlarged all the borders of the land." — Isaiah 26:15 (ASV)

You have increased the nation - That is, the Jewish nation (see the note at Isaiah 9:3). The nation was not only enlarged by its regular increase of population, but many converts attended them on their return from Babylon, and probably many came in from surrounding nations on the rebuilding of their capital.

You had removed it far ... - Or rather, you have extended far all the borders of the land. The word rendered ‘removed’ (רחק râchaq) means usually to put far away, and here it may mean to put far away the borders or boundaries of the nation; that is, to extend them far. The word ‘unto’ is not in the original; and the phrase rendered ‘ends of the earth,’ may mean the borders or boundaries of the land. The parallelism requires this construction, and it is indeed the obvious one, and has been adopted by Lowth and Noyes.