Reference for Bava Batra 336:9

אמר ליה רב אחא בר מניומי לאביי ודלמא רישומו ניכר ותניא נמחק או נטשטש אם רישומו ניכר כשר אמר ליה מי קאמינא שטרא מעליא אל"ף בי"ת בעלמא קאמינא

witnesses [sign] on [clean] paper, [and thus produce duplicate deeds], which [are] invalid.<span class="x" onmousemove="('comment',' They, not knowing that the duplicates were of no legal value, would cease troubling the Master, while no loss to subsequent buyers, (v. supra n. 1) could possibly be involved (v. supra 164a). ');">¹⁵</span> Said R. Aha b. Manyumi to Abaye;<span class="x" onmousemove="('comment',' R. Aha understood Abaye to have instructed his scribe (a) to copy the deeds on clean paper; (b) to erase the text, and (c), to copy the deeds again on these erasures. ');">¹⁶</span>

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