The gemara asks that we see by melons and cucumbers that if he gave inferior Trumah that its Trumah and he has to be Toraim again and we dont make him give it back like we do with kemach for Challah.
The Gemara responds that its different because by cucumbers its medoraysa Trumah m'alya, which Rashi explains that a) you cant give back Trumah to the Baal Habayis and b) there's no chashash of Churvah because even if he eats the rest without hafrashah there's no Issur D'oraysa because he patered the rest anyway with the first hafrashah.
Why doesnt Rashi say poshut that melons and cucumbers are only mechuyav in Trumah Mid'Rabbonan?
Thank you.
Yerachmiel Seplowitz, Monsey< NY, USA
Rashi is not the problem. He can't explain against the Gemara, and the Gemara says that by Kishus, Min ha'Torah there is good Terumah (it doesn't say that there is no Terumah Min ha'Torah at all).
The Gemara wants to say that by Kishus there is no Tevel problem and therefore the suspicion that it won't get Ma'asered again is not serious, as opposed to the case of Nakuv where a real Tevel problem exists and re-Ma'asering is problematic.
You could still ask, "Why is the term d'Oraisa used by the Gemara by Kishus when its only d'Rabanan?" I think that d'Oraisa is a borrowed term . The Gemara means that the major Tevel problem is solved because Terumah was already set aside.
All the best,
Reuven Weiner