Isaiah 54:1

Sing — The prophet having largely discoursed of the sufferings of Christ, and of the blessed fruits thereof, and here foreseeing that glorious state of the church, he breaks forth into this song of triumph. And as the foregoing chapter literally speaks of Christ, so doth this of the church of Christ. This church, consisting at first of the Jews, and afterwards of the Gentiles, had been barren, 'till the coming of Christ. The desolate — The church of the Gentiles, which in the times of the Old Testament was desolate, does now bring forth to God a more numerous posterity than that of the Jews.