Terumos 4:1-2

Terumos 4:1

If a person took part of his terumah and tithes, he may take the rest of his terumah for this stack from it, but not for other produce. Rabbi Meir says he may also take terumah and tithes from it for other produce.

Terumos 4:2

If a person had produce in storage and he gave a seah to a Levite (as first tithe) and a seah to a needy person (as tithe for the poor), Rabbi Meir says he can take eight seah for himself and eat them. (A seah is a measure of volume, approximately 13 liters.) The Sages say he can only take proportionate to what remains of those two seah (i.e., if they still exist in their entirety, he can take the full eight seah. If they were already half-eaten, he can only take four seah.)