Midrash su Levitico 7:18

1) (Vayikra 7:18) ("And if there be eaten of the flesh of the sacrifice of his peace-offerings on the third day, it shall not be accepted. He that offers it shall not bethink himself. It shall be piggul ("rejected"), and the soul that eats of it shall bear his sin.") "And if there be eaten … on the third day, it shall not be accepted": R. Eliezer said: Incline your ear to hear: (Scripture is speaking not of actual eating, but of thinking, i.e.,) "If one thinks to eat of his sacrifice on the third day, it shall not be accepted." R. Akiva said: I would understand the verse (literally) as meaning that if he (actually) ate of it on the third day it becomes unfit. — But it is impossible to say this. For after it has been validated (by the priestly service), can it then become unfit? — Yes, (indeed it may)! For we find in respect to a zav (a man with a genital emission) or a zavah (a woman with a genital emission), or a woman who watches a day (without emission) against a day (of emission), that when they are in a state of taharah (ritual cleanliness) and (again) witness an emission, they annul (that state of taharah) — this (offering), too, if he ate of it on the third day, it becomes unfit. It is, therefore, written (to negate this,) "he that offers" — It is at the time of offering (with wrong intent) that it becomes unfit, and not on the third day (when it is eaten).

1) I might think that (piggul) thought invalidated only outside of its (the offering's) prescribed time. Whence do I derive (that it also invalidates) outside of its prescribed place? It follows by induction, viz.: Time invalidates and bound invalidates. Just as (piggul) thought invalidates outside of the prescribed time it should also invalidate outside of the prescribed bound.

2) Whence do I derive forbidden fats as subject to meilah? (For I would say that the meilah prohibition does not "take" on that of forbidden fats.) From "the sanctified things of the L–rd." I might think that the blood (of holy of holies before sprinkling) was also included. It is, therefore, (to negate this) written "of (and not all of) the sanctified things." Why do you see fit to include forbidden fats and to exclude blood? After the verse includes, it excludes. I include (forbidden) fats, which are like flesh in that they are susceptible of pigul (Vayikra 7:18), nothar (Vayikra 7:17), and tumah and I exclude blood, which is not thus susceptible.