Isaiah has shown Christ speaking 7 centuries before His birth. God said that God and the Spirit have sent Him (Isa. 48:16-17). Further into Isaiah’s prophecy, Jesus said,
“Listen, O coastlands, to Me, And take heed, you peoples from afar! The LORD has called Me from the womb; From the matrix of My mother He has made mention of My name. And He has made My mouth like a sharp sword; In the shadow of His hand He has hidden Me, And made Me a polished shaft; In His quiver He has hidden Me” (49:1-2).
Christ is speaking of being called from His earthly mother’s womb before He was conceived. This is just how the Angel spoke to Mary, Jesus’ mother (Luke 1:30-33).
God did such a great thing by sending Jesus Christ, who is God, in the flesh and birth of an earthly mother. Therefore, God saw that sending His Son must be greater than saving just Judah and Israel. God spoke more about forming Christ in the womb to be His Servant in Isaiah 49:6,
“It is too small a thing that You should be My Servant To raise up the tribes of Jacob, And to restore the preserved ones of Israel; I will also give You as a light to the Nations, That You should be My salvation to the ends of the earth.”
Because God was to send Christ to be a light and salvation to the nations, He said in Isaiah 49:8,
“In an acceptable time I have heard You, And in the day of salvation I have helped You; I will preserve You and give You As a covenant to the people, To restore the earth, To cause them to inherit the desolate heritages;”.
Christ is the covenant to the ends of the earth and to all nations. Therefore, God called for the heavens and the earth to rejoice with singing.
“Sing, O heavens! Be joyful, O earth! And break out in singing, O mountains! For the LORD has comforted His people, And will have mercy on His afflicted” (49:13).