Thy sisters, thine elder and thy younger - The Gentiles, who were before the Jews were called, and after the Jews were cast off, are here termed the elder and younger sister. These were to be given to Jerusalem for daughters; the latter should be converted to God by the ministry of men who should spring out of the Jewish Church. The former, who were patriarchs, etc., profited by the Lamb who was slain from the foundation of the world. Among the latter the Gospel was preached, first by Christ and his apostles, and since by persons raised up from among themselves.
But not by thy covenant - This was the ancient covenant, the conditions of which they broke, and the blessings of which they forfeited; but by that new covenant, or the renewal to the Gentiles of that covenant that was made originally with Abraham while he was a Gentile, promising that in his seed all the nations of the earth should be blessed; that covenant which respected the incarnation of Christ, and was ratified by the blood of his cross.