Rif Pesachim 14a {Pesachim 45b continues ... 46a; 48a-b}

HIDE/SHOW IMAGE
14a

{Pesachim 45b continues}
it need not be burnt.
And we also learnt {tnan}: Anything which is unique as food for humans is impure until it becomes unfit as food for a dog.
This implies that if it becomes unfit to be food for a dog, it is taken out of the status of food and is considered to be mere dust.
And a brayta in the Tosefta also states as much: A kilor {an eye salve - see collyrium} and an asplanit {=compress} and a retiya {compress} in which flour was placed, he need not remove it {=the chametz}. A melogma {poultice} which spoiled, he need not remove.

{Pesachim 46a}
"Dull dough -- if there is there {another dough} the same as it {made at the same time} which exhibits signs of rising, it is forbidden":
What if there is not there the same as it?
Rabbi Abahu cited Rabbi Shimon ben Lakish: {the amount of time} such that one could walk from Migdol Ninveh to Teveria, which is a mil.

Mishna:
How can challah {=the first of the dough given to a Kohen} be separated on Yom Tov {=Pesach} when it is ritually impure?
Rabbi Eliezer says: He should not designate it as such until it bakes.
Ben Beteira says: He should place it in cold water.
Rabbi Yehoshua says: {Pesachim 46b} This is not the kind of chametz that we were warned about not to see or find. Rather he should separate it and lay it aside until the evening, and if it becomes chametz, it becomes chametz.

{Pesachim 48a}
Gemara:
They learnt {in a brayta}: Rabbi says: The halacha is like Rabbi Eliezer. And Rabbi Yitzchak said: The halacha is like Ben Beteira.

And the halacha is like Rabbi Eliezer, as Rabbi rules, for we establish that the halacha is like Rabbi over his colleague.
{Pesachim 48b}
And furthermore, this statement of Rabbi Eliezer is related to this other statement of Rabbi Eliezer, who said that even if one shovels {bread} and places the bread in a basket,