This precious portion seems to be as in answer to what had been said before. The Lord had been giving exceeding great and precious promises to his people, and now his people, as with one voice, makes the Lord a thankful answer, in prayer and praise, that God would do so. It is the language of strong faith, offered up in Christ Jesus. For the arm of the Lord is Christ, Deuteronomy 7:19; hence, when the Prophet complains of the little success of preaching of the gospel, he calls it the arm of the Lord, Isaiah 53:1; and hence the Reader will also perceive that the Prophet is celebrating Christ in that arm of the Lord, which cut Rahab, and wounded the dragon; and dried up the sea, and led his people through. For who is meant by Rahab, but Pharaoh, the dragon, the leviathan; and what sea was this but the Red Sea? This is he, saith Stephen, which was in the Church in the wilderness, Acts 7:38. Reader, how blessed is it to trace Christ, in all the redemption of his people! See those scriptures, Habakkuk 3:8, to the end; Psalms 74:13-14. And observe, in this latter scripture, how the sacred writer makes that triumph of God's people over Pharaoh and his host, to be as meat to them in the wilderness; meaning, that in the experience of the Lord's victory then, they found food to keep alive their faith, in all the after exercises they were called to. And what is the final song of triumph, but the same? Isaiah 35:10; Revelation 15:3.
Related Commentaries of Isaiah 51:9
Isaiah 51:9-11
9 Awake, awake, put on strength, O arm of the LORD; awake, as in the ancient days, in the generations of old. Art thou not it that hath cut Rahab, and wounded the dragon?
10 Art thou not it which hath dried the sea, the waters of the great deep; that hath made the depths of the sea a way for the ransomed to pass over?
11 Therefore the redeemed of the LORD shall return, and come with singing unto Zion; and everlasting joy shall be upon their head: they shall obtain gladness and joy; and sorrow and mourning shall flee away.