Charles Ellicott Commentary Isaiah 51:16

"And I have put my words in thy mouth, and have covered thee in the shadow of my hand, that I may plant the heavens, and lay the foundations of the earth, and say unto Zion, Thou art my people." — Isaiah 51:16 (ASV)

And I have put my words in your mouth ... — Some interpreters assume that, while Isaiah 51:1 was spoken to the Jewish exiles, this, which reminds us of Isaiah 49:2, is addressed to the Servant of the Lord. Of these, some (Cheyne), struck by the apparent abruptness, assume it to be misplaced. There seems no adequate reason for adopting either hypothesis. The words are spoken to Israel, contemplated as in its ideal, as were the others to the actual Israel. It remains true, as ever, that that ideal is fulfilled only in the Servant.

That I may plant. — Noteworthy as the first intimation of the new heaven and the new earth, implying a restitution of all things, of which we find the expression in Isaiah 65:17; Isaiah 66:22.