Reference for Niddah 112:10

אי אמרת חזקתו מתכבס בסטרא לא מתכבס

but if you say that 'it is in the presumptive state of having been properly washed', a stain in a fold may not have been washed out.<span class="x" onmousemove="('comment',' V. p. 393, n. 13. ');">¹⁰</span>

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