Reference for Bava Batra 132:3

אי הכי אפילו חקקו ולבסוף קבעו נמי שאני התם דאיכא תורת כלי עליו בתלוש

because its uncleanness was decreed [only] by the Rabbis. If that is the case,<span class="x" onmousemove="('comment',' That the Rabbis draw no distinction between whether it was first hollowed and then fixed or otherwise, and that their reason in the case of the mikweh is because, as it is only Rabbinical, there is no need to be so particular in regard to 'drawn' water. ');">³</span>

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