Reference for Bava Batra 112:2

שלשה אחים ואחד מצטרף עמהם הרי אלו שלש עדיות והן עדות אחת להזמה:

[ONE FOR EACH YEAR], BUT THE THREE ARE RECKONED AS ONE FOR THE PURPOSE OF DECLARING THE WITNESSES <i>ZOMEMIM</i>.<span class="x" onmousemove="('comment',' I.e., they cannot be declared zomemim till the evidence of all four has been proved to be false, and in that case each pays one-sixth. ');">²</span>

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