Matthew Poole and continuators on Romans 11:18

18. Boast not against the branches: But if thou boast, thou bearest not the root, but the root thee .

i. e. Against the Iews, who, because of their unbelief, are broken off; as if by Nature thou wert better than they, or more worthy of that Grace which is bestowed on thee. The word signifies, Throw not up thy Neck, don't carry thy self Scornfully and Insultingly.

q. d. If any will needs be so Insolent, let them know and consider, That as the Root is not beholding to the branches, but the branches to the Root: So the good Things that the Gentiles have, they receiv'd from the Iews, and not the Iews from them: The Gentile Church is Incorporated into the Iewish, and not the Iewish into the Gentile. Or else the meaning is, Despise not the Iews, for they are the natural branches of the Root that bears them. If thou Insultest over the Branches, thou dost in a manner lift up thy self against the Root: That once bore them, and now bears thee; even Abraham, who is the Father of all them that Believe. Abraham is not the Root, simply and absolutely, but Relatively, or by way of Relation to his Posterity and Off-spring.