Reference for Niddah 121:20

בדקה אחת [וכו']

while in that of a heap you differ?<span class="x" onmousemove="('comment',' Maintaining that, if the examination was continued down to bedrock or virgin soil and no trace of corpse was found, the heap may be regarded as clean despite the presumptive existence of a piece of corpse in one of the heaps. ');">¹⁹</span>

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