Reference for Niddah 71:19

כיון דמעת לעת ליכא מפקידה לפקידה נמי לא גזרו בה רבנן

but according to Rab who said that there existed only one source, why should it suffice for her to reckon her uncleanness from the time of her observation seeing that<span class="x" onmousemove="('comment',' Since that source has also been discharging during the clean period and the present discharge cannot be regarded as a first one. ');">¹⁷</span>

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