Comentário sobre Números 18:29

מכל מתנתיכם תרימו את כל תרומת ה׳ OUT OF ALL YOUR GIFTS YOU SHALL HEAVE EVERY HEAVE OFFERING UNTO THE LORD — Scripture is speaking here of the “Terumah Gedolah” (not of תרומת מעשר, for this is dealt with in verse 28); the meaning is, that if the Levite came to the field before the priest, when the grain has been made into a heap (i.e., after it has been threshed, when it becomes subject to the law of Terumah), and received his tithes before the priest took the Terumah Gedolah from the heap, the Levite must first set apart the fiftieth part (the usual proportion of the crop which the Israelite gives to the priest) of the tithe as “Terumah Gedolah” and then again set apart the תרומת מעשר (i.e. the tithe of his tithe) (Shabbat 127b).

The major terumah… Since “from all of your tithes” (v. 28) implies the terumah of the tithe, then “you must set aside all of the terumah-gifts of Hashem” must refer to the major terumah. But how could this be, for surely an Israelite would have already given the major terumah-gift? Therefore Rashi explains that this is a case where the Levite pre-empted the kohein. This means after threshing, not while the grain was in on the stalks, because if the Levite pre-empted him at that stage he would only be obliged to give the kohein the terumah of the tithe.

V. 29. מכל מתנותיכם וגו׳ (siehe zu V. 25) מכל חלבו: es ist Pflicht, die תרומה von dem Guten und nicht von dem Schlechten zu geben, אין תורמין מן הרעה על היפה (Temura 5a).