Reference for Shabbat 122:2

והתניא איזהו קמיע מומחה כל שריפא ג' בני אדם כאחד

But it was taught: What is an approved amulet? One that has healed three men simultaneously?<span class="x" onmousemove="('comment',' 'Simultaneously' is absent from Rashi's version, but present in cur. edd. and Tosaf., which explains that it refers to three amulets (presumably of exactly the same pattern) worn by three men. Whereas by the previous definition it is sufficient if it has healed three times, even the same person. ');">²</span>

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