Review Answers Shiur 7

1) The source is the Gemora Baitza. The Gemora says that you can be add to branches that are muktza which is an issur d'rabbanan in order to be mevatel them.

2) To "marbeh b'yadayim" means to add heter to a ta'aruvot in order that there is enough heter to mevatel the issur in the ta'aruvot.

3) There are 3 ways are:
1. Rashba. We allow marbeh b'yadayim in all issurei d'rabbanan
2. Tosefot and Rambam. We allow marbeh b'yadayim in issurei d'rabbanan that have no d'oraita basis, but not in other issurai d'rabbanan.
3. Rosh and Ra'ah. We only allow marbeh b'yadayim in issurei d'rabbanan when no ha'na'ah is derived when the issur is b'ain.

4) An issur d'rabbanan that has a source from the Torah is a rabbinic siyag; one that has no source from the Torah is a gezeira. An example of the former is chicken and milk which is a siyag for basar b'chalav. An example of the latter is muktzeh which has no d'oraita basis. The nafka mina is whether or not we may marbeh b'yadayim to mevatel the issur -- Rashba always allows us to marbeh b'yadayim; Tosefot only allows it for a gezeira with no d'oraita foundation.

5) If milk falls into chicken, the Rambam will allow additional chicken to be added to mevatel it. The Mechaber agrees; everyone else forbids it.

6) Halacha l'ma'aseh is that sephardim may add chicken; ashkenazim may not.

7) 1. In a case where oil is left over from the Chanukah Menorah became mixed with other oil and was not batel b'shishim, we cannot be marbeh beyadayim.
2. In other cases of issurei hana'ah.

8) A "kli shemishtamshin bo b'shefa" is a kli that is only used with lots of heter at once and there will always be 60. An example is a pot that is used to boil water to make pasta is typically filled with a lot of water at one time prior to boiling.

9) According to the Mechaber, the kli shemishtamshin bo b'shefa need not be kashered prior to use providing it absorbed only a small amount of issur. This is because the amount of issur is so small that it will be mevutal by the shefa in the kli. This is even more true if the issur is lifgam and even more so if the issur is d'rabbanan. The Taz and the Shach hold that only in a case where the issur imparts a bad taste to the food it is permitted to use the kli without kashering for a large quantity of food. The Mishbetzot Zahav adds that if the issur is midrabbanan AND the kli is mishtamshin b'shefa, then perhaps we can be meikil and use the kli without kashering it.