Isaiah 55:4

"Behold" introduces this verse and the next, and suggests comparison of them. The readers are not only to listen to what the Lord says but to look at what He presents. God is the speaker, but who is the "him" that is a witness to the nations and a leader and commander for the peoples? It could be David (Isaiah 55:3), who witnessed to the character of Yahweh in his ministry. It could be Messiah, who would be a witness (light) to the nations and lead them. It is probably not Israel, since "him" is an unusual way of referring to Israel in this context. Nor is it the people of God more generally. I think the witness is the Servant Messiah, whom David anticipated and prefigured. Watts believed he was Darius. [Note: Watts, Isaiah 34-66, p. 246.] "The faithful mercies of David" (Isaiah 55:3) point beyond David; they are the faithful mercies promised to David.

". . . the book of the King ([Isaiah] chapters 1-37) portrayed the Messiah as the fulfilment [sic] of the ideal in its royal aspects, but now Isaiah brings the values of the Servant-Messiah within the basic Davidic-Messianic model. It is the Servant, with his prophetic task (Isaiah 42:1-4; Isaiah 49:2-3; Isaiah 50:4), who fulfils the role of Davidic witness to the world [cf. Isaiah 49:1]." [Note: Motyer, pp. 454-55.]