Sing, heavens! Shout for joy, earth! Let the mountains burst into song! The Lord will comfort his people; he will have pity on his suffering people.” (Isaiah 49:13, GNB)

More personification here of inanimate objects.  The heavens should sing; the earth should shout for joy; the mountains should burst into song.  God’s people have been dispersed into exile from the far north to Aswan in the far south of Egypt.  God has not forgotten his people, nor has he abandoned them.  “He will have pity on his suffering people.”

This is powerful medicine when God’s people are suffering as happens so often.

John Calvin: Let us therefore remember, that whenever the Lord promises anything, we ought to add thanksgiving, that we may more powerfully affect our hearts; and next, that we ought to raise our minds to the power of God, who exercises a wide and extensive dominion over all the creatures; for as soon as he lifts his hand, “heaven and earth” are moved.