Sing for joy, O heavens, and exult, O earth; break forth, O mountains, into singing! For the LORD has comforted his people and will have compassion on his afflicted.
The scope of these verses is to show that the return of the people of God out of their captivity, and the eternal redemption to be wrought out by Christ (of which that was a type), would be great occasions of joy to the church and great proofs of the tender care God has of the church. I.
Commenting on Isaiah 49:13-17
Sing, O heavens, and be joyful, O earth,.... Which may be understood of the heavens, and the earth by a personification, a figure usual in Scripture, to express the greatness of the benefit received, and to raise thankfulness and admiration in the hearts of God's people; see Psa 90:11 or by the heavens may be meant the angels in heaven, who, as they rejoice at...
So Rev 12:12. God will have mercy on the afflicted, because of His compassion; on His afflicted, because of His covenant.