Reference for Temurah 42:20

בירושלים ליתי מעשר שני בכל הרואה קמ"ל

Scripture therefore says: 'Thou shalt eat before the Lord thy God the tithe of thy corn and of thy wine and of thine oil, and the firstlings of. , etc.' , thus comparing second tithe with firstling as follows: Just as a firstling is not eaten except within the wall [of Jerusalem], similarly [second] tithe is not eaten except within the wall [of Jerusalem].

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