Charles Ellicott Commentary Romans 11:19-20

"Thou wilt say then, Branches were broken off, that I might be grafted in. Well; by their unbelief they were broken off, and thou standest by thy faith. Be not highminded, but fear:" — Romans 11:19-20 (ASV)

It might be possible for the Gentile to claim a special providence in his substitution for the Jew. He should rather be reminded that there is a condition—faith—which is attached to this substitution; this he must be careful to observe, or else he will lose all that he has gained.