27 And Isaiah says about Israel, Even if the number of the children of Israel is as the sand of the sea, only a small part will get salvation:

Matthew Henry's Commentary on Romans 9:27

Commentary on Romans 9:25-29

(Read Romans 9:25-29)

The rejecting of the Jews, and the taking in the Gentiles, were foretold in the Old Testament. It tends very much to the clearing of a truth, to observe how the Scripture is fulfilled in it. It is a wonder of Divine power and mercy that there are any saved: for even those left to be a seed, if God had dealt with them according to their sins, had perished with the rest. This great truth this Scripture teaches us. Even among the vast number of professing Christians it is to be feared that only a remnant will be saved.