John Calvin Commentary Isaiah 54:3

"For thou shalt spread aboard on the right hand and on the left; and thy seed shall possess the nations, and make the desolate cities to be inhabited." — Isaiah 54:3 (ASV)

Because thou shalt be multiplied. Now follows the reason why he commanded the cords to be lengthened for enlarging the tents. The reason is that a moderate space would not contain a numerous people, whom the Lord will gather into one from every quarter. Now, because Judea was hideous on account of its ruins and desolation, he says that the forsaken cities shall be inhabited.