Eruvin 31B

ואת אכסניא דמאי.

and one may also feed soldiers demai.

אמר רב הונא: תנא, בית שמאי אומרים: אין מאכילין את העניים דמאי, ובית הלל אומרים: מאכילין את העניים דמאי.

Rav Huna said: It was taught that Beit Shammai say: One may not feed the impoverished demai. And Beit Hillel say: One may feed the impoverished demai. The halakha is in accordance with the opinion of Beit Hillel.

ובמעשר ראשון שנטלה כו׳. פשיטא! לא צריכא, שהקדימו בשבלין, ונטלה ממנו תרומת מעשר, ולא נטלה ממנו תרומה גדולה.

We learned in the Mishnah: One may establish an eiruv with first tithe whose teruma has been taken. The Talmud expresses surprise: It is obvious that if the teruma was already taken there is no problem. Why is it necessary to state it may be used for an eiruv? The Talmud answers: It is only necessary to teach this halakha in a case where the Levite preceded the priest while the grain was still on the stalks, i.e., the Levite took his tithe before the grain was threshed and before the priest took the teruma; and the teruma of the tithes was taken from it but teruma gedola was not taken from it. Therefore, since the teruma is generally separated first, a portion of the first tithe that the Levite took should have been separated as teruma.

וכדרבי אבהו אמר ריש לקיש, דאמר רבי אבהו אמר ריש לקיש: מעשר ראשון שהקדימו בשבלין ⁠— פטור מתרומה גדולה, שנאמר: ״והרמותם ממנו תרומת ה׳ מעשר מן המעשר״. מעשר מן המעשר אמרתי לך, ולא תרומה גדולה ותרומת מעשר מן המעשר.

And this is in accordance with the opinion that R' Abbahu said that Reish Lakish said, as R' Abbahu said that Reish Lakish said: First tithe, in a case where the Levite preceded the priest while the grain was still on the stalks, is exempt from teruma gedola, as it is stated: “And you should set apart from it a gift for YHWH, even a 1/10th part of the tithe” (Numbers 18:26), from which the following inference is made: a 1/10th part of the tithe, i.e., the teruma of the tithe, I told you, the Levite, to separate. And I did not tell you to separate teruma gedola and the teruma of the tithe.