Reference for Chullin 50:39

אי רבנן אע"ג דהחמיץ

If the Rabbis, then even though it has fermented [it should not be purchasable with Second Tithe money], and if R'Judah, then even though it has not fermented at all [it should be purchasable with Second Tithe money]! - R'Nahman said, in the name of Rabbah B'Abbuha,

Jastrow

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