4:21 {6} Tell me, ye that {u} desire to be under the law, do ye not hear the law?
(6) The false apostles urged this, that unless the Gentiles were circumcised Christ could profit them nothing at all, and also this dissension of those who believed in the circumcision, against those who believed in the uncircumcision, both these things being full of offence. Therefore the apostle, after various arguments with which he has refuted their error, brings forth an allegory, in which he says that the Holy Spirit did through symbolism let us know all these mysteries: that is, that it should come to pass that two sorts of sons should have Abraham as a father common to them both, but not with equal success. For as Abraham begat Ishmael by the common course of nature, of Hagar his bondmaid and a stranger, and begat Isaac of Sara a free woman, by the virtue of the promise, and by grace only, the first was not heir, and also persecuted the heir. So there are two covenants, and as it were two sons born to Abraham by those two covenants, as it were by two mothers. The one was made in Sinai, outside of the land of promise, according to which covenant Abraham's children according to the flesh were begotten: that is, the Jews, who seek righteousness by that covenant, that is, by the Law. But they are not heirs, and they will at length be cast out of the house, as those that persecute the true heirs. The other was made in that high Jerusalem, or in Zion (that is, by the sacrifice of Christ) which begets children of promise, that is, believers, by the power of the Holy Spirit. And these children (like Abraham) do rest themselves in the free promise, and they alone by the right of children will be partakers of the father's inheritance, whereas those servants will be shut out.
(u) That desire so greatly.
4:21 Tell me, ye that desire to be under the law. What troubled him was their tendency to accept the obsolete law of Moses. He now addressed all such a question.
Do ye not hear the law? Will they hear the law itself?
4:21 Do ye not hear the law - Regard what it says.
4:21-27 The difference between believers who rested in Christ only, and those who trusted in the law, is explained by the histories of Isaac and Ishmael. These things are an allegory, wherein, beside the literal and historical sense of the words, the Spirit of God points out something further. Hagar and Sarah were apt emblems of the two different dispensations of the covenant. The heavenly Jerusalem, the true church from above, represented by Sarah, is in a state of freedom, and is the mother of all believers, who are born of the Holy Spirit. They were by regeneration and true faith, made a part of the true seed of Abraham, according to the promise made to him.
