Break forth into joy - Jerusalem, at the time here referred to, was lying waste and in ruins. This call on the waste places of Jerusalem to break out into expressions of praise, is in accordance with a style which frequently occurs in Isaiah, and in other sacred writers, by which inanimate objects are called on to manifest their joy (see the notes at Isaiah 14:7-8; Isaiah 42:11).
For the Lord hath comforted his people - That is, he does comfort his people, and redeem them. This is seen by the prophet in vision, and to his view it is represented as if it were passing before his eyes.
He hath redeemed Jerusalem - On the meaning of the word ‘redeemed,’ see the notes at Isaiah 43:1-3. The idea here is, that Yahweh was about to restore his people from their long captivity, and again to cause Jerusalem to be rebuilt.