Reference for Gittin 66:7

אמר רב אשי אי בעדי כתיבה הכי נמי הכא במאי עסקינן בעדי הולכה

or is his reason that in his opinion a thing which has been done in the presence of ten can only be undone in the presence of ten, and therefore even if he said 'all of you' [he can only countermand the order when they are all together]?<span class="x" onmousemove="('comment',' And the two whom he forbids can disregard his instruction. ');">⁷</span>

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