[Avodah] The Jews fed the Mitzrim During Makas Choshech

[Zev Sero]

The Bavli does not mention anywhere a limit on how long it's possible
to fast.  The Rambam paskens halacha lema'aseh that the limit is seven
days, not three; AFAIK there is no contrary opinion.
http://mechon-mamre.org/i/6101.htm#7
http://mechon-mamre.org/i/6105.htm#20

> So, it's possible enough not to be a shevu'as shav (my half wrong), it is
> still singled out as being incredibly unlikely -- which I am considering
> my "half right", since clearly a whole nation didn't survive that way.

On the contrary, Esther 4:16 proves that it's perfectly possible for an
entire nation to do it, and not at all unlikely; kal vachomer if one is
physically constrained from eating rather than having to restrain oneself
only by force of will.

As for the Y'mi, there are two possible answers.  The Shyarei Hakorban
says it's a ta`us sofer, and should say seven days; and the Rambam
argues and says that it's impossible and one is lokeh immediately and
may eat.   Another possibility is that the Y'mi is merely contrasting
eating with sleeping and saying that while it's impossible to go three
days without sleep going three days without food or drink is merely
difficult, so he has to keep his word as long as he can.  If this is so,
then when the Rambam gives a limit of seven days he may be relying on his
own knowledge as a doctor.  The Or Sameach suggests that the Rambam's
source *may* be from Yoma 4b, which says that it takes six days to get
rid of all the food in a person's system.




-- 
Zev Sero        "Natural resources are not finite in any meaningful
zev at sero.name    economic sense, mind-boggling though this assertion
                  may be. The stocks of them are not fixed but rather
		 are expanding through human ingenuity."
		                            - Julian Simon