Romans 11:17
But if some of the branches were broken off, and you, being a wild olive, were grafted in among them, and became partaker with them of the root and of the richness of the olive tree;
WEB
And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree;
KJV
What Romans 11:17 means
It is Paul's warning to non-Jewish Christians not to feel superior to the Jewish people, because their faith grows out of Israel's root and depends on it, and not the other way around.
These lines come from a letter the apostle Paul wrote to the young church in Rome, a community of both Jewish and non-Jewish believers. In the chapter around them, Paul is working out how Gentiles, people from outside Israel, fit into a story that began with the Jewish people. He reaches for a picture from farming: an olive tree, standing for Israel and God's promises to it. Some branches have been broken off, and a wild branch has been grafted in to share the life of the tree.
The wild branch is the Gentile believer. Paul's warning is blunt: do not look down on the branches that were already there. A grafted branch draws its life from the root; it does not feed the root. The faith the newcomers have joined grew from Jewish soil, and forgetting that turns gratitude into arrogance. The verse is a caution against spiritual pride and a reminder of where the whole thing came from.