Reference for Shevuot 22:2

ואמאי לימא לב בית דין מתנה עליהן

R'Eleazar and R'Simeon say: They pasture till they become unfit [for sacrifice],<span class="x" onmousemove="('comment',' By becoming blemished.');">³</span> then they are sold, the money going as a donation [to the Temple treasury], for a congregational sin-offering does not die.<span class="x" onmousemove="('comment',' I.e,, is not starved to death. Sin-offerings of individuals are, in certain circumstances, starved to death; but not congregational sin-offerings. V. Tem. 15a.');">⁴</span> - Why [should they be starved, or pasture till they become blemished]?

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