פירוש על עבודה זרה 71:22

According to Rav, Daniel (from the Bible) made a decree against using Gentile oil. While the Talmud does not explain here what Daniel’s reasoning was, we can assume that it was to prevent Jews from fraternizing with non-Jews. In other words, the prohibition of Gentile oil was a step to keep Jews from assimilating with non-Jews.
Shmuel seems to fear that the oil actually has prohibited ingredients in it. While there is nothing wrong with the oil, if the oil was used in vessels that had been previously used with forbidden foods, then the oil is forbidden.

The Talmud recalls that R. Judah [assumed below to be R. Judah Hanasi, but probably referring to his grandson], the rabbis took a vote and allowed Jews to use Gentile oil. If the reason for the prohibition was that the vessels of non-Jews imparted forbidden flavor to the oil, then we can understand why it was overturned. Some rabbis thought that since this flavor does not improve the taste of the oil, the oil is permitted.

If Rav is correct, that Daniel made a decree to prohibit oil, then how could another court overturn it. Later courts are almost never allowed to overturn decisions made by earlier courts.

Rav discounts Shmuel’s statement because it is attributed to R. Simlai who is from Lod, and in Lod they are not respectful of rabbinic statements.
Shmuel boldly offers to send for Simlai to check to see if his statement is accurate. Rav becomes embarrassed. He does not want to criticize Simlai to his face.

Here we see the source of the notion that Jews should not eat certain foods made by non-Jews. Daniel refused to eat the king’s bread or drink his wine. The rabbis read from this that he did not drink their oil either. After all, oil is like wine and bread—it is a product refined from raw ingredients. The dispute between Rav and Shmuel is over whether this was a decree for all of Israel. Rav holds that it was, and therefore it can never be overturned. Shmuel holds that this was a private behavior, not obligatory for all of Israel, forever.

The Talmud cites a counter tradition. The food products made by Gentiles were prohibited not by Daniel, but during the period of Hillel and Shammai when they made “18 decrees.” The discussion of these decrees is found in the beginning of Tractate Shabbat.
The Talmud rejects the notion that Daniel made the decrees, it was rejected, and then Hillel and Shammai remade it. If that was true, why would Rav have said that Daniel made the decree? After all, it was rejected.

The Talmud resolves the difficulty by suggesting that the decree against oil spread. First it began with a decree against using these products in the city, where the problem of fraternization was greatest. Then a later group of rabbis, perhaps a bit more zealous than Danied, added that using these products is forbidden even outside of the city, even though there is probably little or no concern there for fraternization.

As we learned above, R. Yehudah Hanasi (the grandson of the rabbi who edited the Mishnah) undid the decree on Gentile oil. But how could he do this? Surely, a later court cannot annul the decrees of the earlier court, and all the more so if the earlier decree was one of the 18 things that were decreed upon by Bet Hillel and Bet Shammai!

This entire section proves the fascinating concept that since most Jews did not observe the oil prohibition, the observance can be nullified by a later court. Telling Jews they cannot use Gentile oil is a decree that people could not live with. Seeing that people were not observing the decree, Rabbi Yehduah Hanasi annulled it altogether.
This is a powerful statement concerning one source of Jewish authority. Jewish authority stems not just from what rabbis tell people to do, or from what the books tell people to do, but also from what practices people accept upon themselves. Put another way, people are obligated to accept certain practices simply because other people are practicing in that way.