Ex 15:1, Ps 98:1-2
In the Old Testament, Moses sang the song of the Lamb immediately after crossing the Red Sea, praising God. (Ex 15:1, Psalm 98:1-2)
Ex 15:1 Then sang Moses and the children of Israel this song unto the Lord, and spake, saying, I will sing unto the Lord, for he hath triumphed gloriously: the horse and his rider hath he thrown into the sea.
Psalm 98:1 O sing unto the Lord a new song; for he hath done marvellous things: his right hand, and his holy arm, hath gotten him the victory. 2 The Lord hath made known his salvation: his righteousness hath he openly shewed in the sight of the heathen.
Moses knew that the coming Christ would become the Lamb of God to save us. (Rev 15:3-4)
Rev 15:3 And they sing the song of Moses the servant of God, and the song of the Lamb, saying, Great and marvellous are thy works, Lord God Almighty; just and true are thy ways, thou King of saints. 4 Who shall not fear thee, O Lord, and glorify thy name? for thou only art holy: for all nations shall come and worship before thee; for thy judgments are made manifest.