Actually I can’t recall a single instance where Jesus cites prior rabbinic sources. This doesn’t mean he didn’t do so, only that those who wrote the Gospels chose not to include those citations if in fact he made them— anything to separate Jesus from his Jewish heritage and promote him as a unique teacher and Son of God.
As for the Pharisees being scandalized, I would say it is, in a strange and intriguing way, the case of the pot calling the kettle black.
While it became customary to honor one’s teachers by citing their names, the rabbis cited in the Mishnah, the earliest codification of rabbinic teaching, did exactly what Jesus did, i.e. they espoused teachings without reference to earlier sources. Later rabbinic commentators on the Mishnah were careful to find links between the Mishnah and the much older Torah, but the Mishnaic teachers themselves claimed an authority separate from the Written Torah, asserting (without any outside corroboration) that God gave two Torahs on Mount Sinai. The Written Torah that was placed into the hands of the Priests, and the Oral Torah, the key to understanding the Written Torah properly, was passed down through Joshua, the Elders, and the Prophets, to the Pharisaic sages themselves.
The early rabbis believed that they embodied the Torah, and that their teachings were Torah. Jesus did the same. The difference, and it is a huge one, is that the rabbis operated within a large community of scholar-saints who challenged one another’s teachings in order to separate truth from mere opinion, while Jesus appears to make his teachings without the benefit of colleagues.
I can see how for many that bold assertion of his own authority was as scandalous to the Pharisees as their bold assertion of authority was to the Sadducees for whom only the Written Torah was authentic revelation.
Regarding the word “neighbor,” I also think it is the great issue of our time. I’m not so sure it was the issue that drove the wedge between Jews and Jewish Christians in the late first century, however.
The battle between the Gentile Christianity of Paul and the Jewish Christianity of Peter and James could certainly be seen as a battle over “neighbor,” but with regard to the larger Jewish world I suspect that the real divide came with the refusal of Jewish Christians to join with their fellow Jews in their war of liberation against Roman occupation.
Believing as they did that Jesus was to return within their lifetimes, entering into a bloody war with Rome made no sense to followers of Jesus. And it is not hard to imagine that early Christians who were being persecuted by Rome were more than happy to have the Romans preoccupied with some other people for a while. So I think it was more a matter of “you’re with us or your against us.”
Yet Jesus’ widening of the concept of “neighbor” was revolutionary. His was an open table fellowship that in our day needs to be broadened even more.
Controlling access to Jesus’ table is part of the politics of religion, but broadening our understanding of “neighbor” to include not only all human beings but all beings in general is essential for the survival of our species.
If we understood that all life was our “neighbor,” that the earth in all her diversity was our “neighbor,” that the cosmos itself is our “neighbor,” we would live on this planet in a way that honored the sacredness of life in all its forms. It is because we have defined “neighbor” too narrowly that we are on the brink of destroying the one table that sustains us.
Perhaps we should start a movement called “God’s Table” that promotes a deep ecological neighborliness (using the word “ecological” in the sense that all beings are interdependent), and that would foster peace among people and between people and the planet. That is a table at which I would be honored to sit.