Reference for Niddah 138:19

אין נדה אלא שמתה נדה

<b><i>MISHNAH</i></b>. IF A <i>ZAB</i>, A ZABAH, A MENSTRUANT, A WOMAN AFTER CHILDBIRTH OR A LEPER HAVE DIED [THEIR CORPSES] CONVEY UNCLEANNESS BY CARRIAGE<span class="x" onmousemove="('comment',' This is discussed in the Gemara infra. ');">¹⁸</span>

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