Study Guide Shabbat 131 Today's daf is sponsored by Idana Goldberg and Michael Kellman in celebration of Idana's grandfather, Meyer Weitz's 100th birthday. Mr. Weitz loves studying Talmud and has always been a strong proponent of women's advanced Talmud study. And by Susan Fisher in memory of her father, Eliezer ben Shraga Pharvish Allweis z"l on his yahrzeit. "He loved learning and filled our home with sifrei kodesh and the books which made limmud Torah a joy." And by Vicki Gordon in memory of her father Yisroel (Izzy) Herzog z"l, a giant in Chesed - "I miss him every day." The gemara brings two explanations of Rav's statement where he distinguishes between carrying in an alley without a proper eiruv (just one beam either horizontal or vertical) when 1. there was an eiruv done between the houses and the courtyard - in that case one is not permitted to carry in the alley more than 4 cubits in a case without a proper eiruv in the alley - and when 2. there was no eiruv between the houses and the courtyard - one is then not permitted to move items that are in the alley more than 4 cubits. Why does he distinguish between those two cases? Rabbi Eliezer holds that preparations for a brit milah are permitted. However, he doesn't hold this for every mitzva. For which mitzvot does he hold this way and for which does he not? From where is each derived from and why can't we learn from one to the other - why does each need its own drasha?