Mishnah for Yevamot 13:4

A seah of unclean terumah that falls into one hundred seahs of clean terumah: Bet Shammai prohibits, But Bet Hillel permits. Bet Hillel said to Bet Shammai: since clean [terumah] is forbidden to non-priests and unclean [terumah is forbidden] to priests, then just as clean [terumah] is brought up, so too unclean [terumah] can be brought up. Bet Shammai answered them: No! If hullin which is treated more leniently [in that it is permitted to non-priests] allows us to bring up clean [terumah that falls into it], does terumah [which is more stringent in that it is forbidden to non-priests] also allow us to bring up that which is unclean? After [Bet Shammai] had agreed [with Bet Hillel], Rabbi Eliezer said: it should be taken out and burned. But the sages say: it is gone, on account of its being a tiny [portion of the whole mixture].

If one had inherited seventh year produce or had received them as a gift: Rabbi Eliezer says: they must be given to anyone who eats them. But the sages say: the sinner must not benefit, rather it should be sold to anyone who eats it, and its price divided among everyone. If one eats dough of seventh year [produce] before the hallah was taken from it, he has incurred thereby the death penalty [at the hands of heaven].