Reference for Bekhorot 52:9

תנא נשר להודיעך כחן דרבנן תנא תולש להודיעך כחו דעקביא:

R'Eleazar reported in the name of Resh Lakish: Wherever the root [of the wool] is turned towards its head.<span class="x" onmousemove="('comment',' The wool being folded up in the centre so that the two tops of the wool appear outside.');">³</span>

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