Midrash for Numbers 18:27

I might think, (that it is tithed) even if it has not been completely processed (for eating); it is, therefore, written (Bamidbar 18:27) "as corn from the threshing floor and as the fullness (i.e., ripeness) of the pit."

(Bamidbar 18:27) "And your terumah will be accounted for you as corn from the threshing floor and as the fullness of the pit": R. Yishmael says: When is your terumah accounted for you as corn from the threshing floor? When you have taken it as prescribed (i.e., a kind for its kind, new for new, etc. [see above]). If you have not taken it as prescribed, it is not thus accounted for you. Variantly: "And your (the Levites') terumah (terumath ma'aser) will be accounted for you as corn from the threshing floor" (terumah gedolah). Now what do we learn from terumah (gedolah) to terumath ma'aser? It (terumah gedolah) comes (apparently) to teach (something), and it ends up being learned (i.e.,) Just as terumath ma'aser is obligatory, so, terumah (gedolah) is obligatory. Abba Eliezer b. Gomel says: Scripture comes to teach you that just as terumah (gedolah) may be taken by estimate and by thought (i.e., without actually handling it), so, terumath ma'aser may be taken by estimate and by thought. "as corn from the threshing floor and as the fullness of the pit": Why is this stated? From (26) "then you shall separate from it," I might think that he could take ears (of grain as terumah) for grain; grapes, for wine; and olives, for oil; it is, therefore, written "as corn from the threshing floor," i.e., (he may take) from what is processed — whence they ruled; (He may take terumah:) from grain, from the time that it (i.e., its pile) has been evened; from wine, from the time that it is skimmed; from oil, from the time that it has dripped down into the trough. (Ibid. 28) "Thus shall you, too, separate the terumah of the L-rd": Why is this written? From (26) "And to the Levites shall you speak, and you shall say to them: When you take from the children of Israel, etc.", (I would say:) The children of Israel give ma'aser to the Levites, but the Cohanim do not give ma'aser to the Levites. And since they do not give ma'aser to the Levites, I might think that they could eat it (the produce) tevel (i.e., untithed); it is, therefore, written: "thus shall you separate, you (the Cohanim), too, the terumah of the L-rd." (i.e., the Cohanim separate terumah, and ma'aser, and terumath ma'aser which reverts to them.) R. Yishmael says: This (derivation) is not needed, for if challah, which does not obtain with all produce (i.e., with all the varieties of grain), obtains with the produce of Cohanim, then ma'aser, which does obtain with all produce, how much more so should it obtain with all the produce of Cohanim! What, then, is the intent of "Thus shall you separate, you, too"? I might think that only the ma'aser of an Israelite (is subject to terumath ma'aser). Whence do I derive the (same for) their (the Levites') own tithe (i.e., the tithe that they separate from what is theirs)? It is, therefore, written "Thus shall you separate, you, (the Levites,) too." (Ibid. 29) "From all of your gifts, etc." Scripture hereby teaches that ma'aser obtains with all (produce [see above]) — whence you rule to terumah (i.e., terumath ma'aser), viz.: If ma'aser, the "lighter," (not being subject to the death penalty), obtains with all produce), then terumah, the "graver," (being subject to the death penalty, [viz. Vayikra 22:9]), how much more so does it obtain with all (produce [of first tithe])! Variantly: If ma'aser (second tithe), which does not obtain in the third and sixth year (of shemitah, [being replaced by poor-tithe]), obtains with all (produce), then terumah, the graver, how much more so should it obtain with all (produce [of second tithe])! Issi b. Menachem says: If ma'aser (second tithe), which comes only as an incentive to fear and to learning (viz. Devarim 14:23), obtains with all (produce), how much more so does it obtain with the "graver," terumah! (Bamidbar, Ibid.) "And you shall give of it the terumah of the L-rd to Aaron the Cohein": Just as Aaron was a chaver (a Torah scholar, so the (other) Cohanim (to receive the priestly gifts, should be chaverim) — whence it was ruled: Priestly gifts should be given only to a chaver. (Ibid. 29) "From all of your gifts shall you separate all the terumah of the L-rd. From all of its best (shall you separate) its hallowed part from it." Is Scripture here speaking of terumah gedolah or of terumath ma'aser? "from all of your tithes" (28) speaks of terumath ma'aser. How, then, is "From all of your gifts shall you separate all the terumah of the L-rd" to be understood? As referring to terumath gedolah. (Devarim 18:4) "The first of your corn, your wine, and your oil … shall you give to him": This is obligatory. You say it is obligatory, but perhaps it is optional! It is, therefore, written (Bamidbar 11:29) "shall you separate all the terumah of the L-rd" — It is obligatory and not optional. These are the words of R. Yonathan. "from all of its best, its hallowed part from it.": So that if it (terumath ma'aser) fell (back) into it (what it was taken from), it "hallows" it — whence they ruled: Terumah is "neutralized" (from its hallowed state) if it fell into one hundred parts of non-terumah when (it is) one to (that) one hundred. This tells me only of terumah that is (ritually) clean. Whence do I derive (the same for) terumah that is tamei, (that if it fell into a hundred of clean terumah, it is neutralized in such a mixture?) It follows a fortiori, viz.: [Note: The translator, with all his consultation of the commentaries, has not been able to render meaningfully what follows (from here until #122)]