Terumot, Chapter One, Mishnah Nine
This mishnah continues to deal with the topic of giving terumah from finished produce for unfinished produce.
1) They may give terumah from oil for pickled olives, or from wine for grapes made into raisins.
2) Behold, he gave terumah from oil for olives intended for eating, or from [other] olives for olives intended for eating, or for wine for grapes intended for eating, of from [other] grapes for grapes intended for eating, and he decided afterwards to press them, he need not give terumah again.
Section one: Pickled olives and raisins are finished produce. Therefore, he can give terumah from oil or wine in order to exempt them.
Section two: In all of these cases, one at first gives terumah from finished produce for produce that he intends to eat in its current state. This is okay because one can give terumah from one finished product (wine or oil) in order to exempt another finished product (olives or grapes intended for eating). Then after having already separated terumah to exempt these olives or grapes that he thought he was going to eat, he decides that he does want to press them and make them into wine or oil. Now it turns out he separated terumah from finished produce for unfinished produce, which is, as we have learned, a no-no. Nevertheless, since when he did separate the terumah he did it correctly, he need not give terumah again.