Bartenura to Mishnah Yadayim 4:6 explains the name as follows:
פרושים. לחכמי ישראל היו קורין פרושים, לפי שאוכלין חוליהן בטהרה ופרושים ממגע עם הארץ, דתנן בגדי עם הארץ מדרס לפרושים:
To the Sages of Israel [the Tzedukim] would call Perushim [lit. “those who separate”], for they would eat their non-sacred food in purity and separate from touching Amei Ha’aretz. As we taught in the Mishnah (Chagigah 2:7): “The clothing of Amei Ha’aretz [contaminates by] treading for Perushim.”
Originally, when I read this Bartenura, I interpreted it to mean that the Tzedukim came up with the name; perhaps they meant it disparagingly, that the Chachamim think they're so great, they don't have to mingle with the common people. The Chachamim, on the other hand, took the term as a symbol of pride.
That's what I thought, until I was reminded of Kiddushin 66a, recalling an incident involving several Chachamim who were killed at a banquet held by King Yannai, which began with this comment:
ויאמר אלעזר בן פועירה לינאי המלך ינאי המלך לבם של פרושים עליך
And Elazar ben Po'irah said to King Yannai, "The hearts of the Perushim are against you."
King Yannai was Shimon ben Shetach's brother-in-law, Shimon ben Shetach was Antigonos Ish Socho's teacher, and Antigonos was Tzadok's and Baisos's teacher. Thus, the term "Perushim" was in use two generations before Tzedukim even existed!
My question, therefore, is twofold:
- Who first used the term Perushim to refer to the Chachamim?
- What was their motivation in doing so? That is, very nice that the term refers to that they separated themselves from Amei HaAretz, but why did this person feel the need to come up with this name? Did they mean it disparagingly, or complimentary?