Jamieson, Fausset & Brown

Boast not against the--rejected branches. But if thou--"do" boast--remember that thou bearest not--"it is not thou that bearest" the root, but the root thee--"If the branches may not boast over the root that bears them, then may not the Gentile boast over the seed of Abraham; for what is thy standing, O Gentile, in relation to Israel, but that of a branch in relation to the root? From Israel hath come all that thou art and hast in the family of God; for "salvation is of the Jews" (Joh 4:22).