Kiddushin 56: Holy Economics
More on the second tithe, ma'aser sheni - as a paradigm of deconsecrating the produce, and redeeming it, eventually. For example, you can't (or shouldn't) use ma'aser sheni money to purchase an animal outside of Jerusalem. Also, a new mishnah, with prohibited items that cannot be used for kiddushin -- because they are prohibited for benefit (items that a user can't get any benefit from, without incurring a violation).
The skinny
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