Demai 5:9-10

Demai 5:9

One may take tithes from (tevel) produce of a Jew’s field for produce of a non-Jew’s field, or from a non-Jew’s produce for a Jew’s (tevel), or from a Jew’s (tevel) produce for a Samaritan (quasi-Jew)’s, or from one Samaritan’s for another Samaritan. Rabbi Eliezer does not permit tithes to be taken from one Samaritan’s produce for another (because one of them may have already tithed and one can’t take obligatory tithes from produce that has already been tithed).

Demai 5:10

A pot with a hole in the bottom is halachically the same as the ground. If one gives terumah (the portion that goes to a kohein) for produce from such a pot for produce from the ground, or vice versa, the terumah is valid. (One may even do this intentionally, at the outset.) If he took terumah from produce grown in a pot without a hole for produce from a pot with a hole, what he separated must be treated as terumah (and given to a kohein) but he must also separate terumah again properly. If he took terumah from produce grown in a pot with a hole for produce from a pot without a hole, it is terumah but the kohein cannot eat it until he himself takes terumah and maaser from it. (The one who took the terumah separated from obligated produce for exempt produce. This is considered tevel – untithed produce.)