Reference for Sanhedrin 53:5
מאי בינייהו איכא בינייהו דאסהידו בי תרי בחד אי נמי דפסלינהו בגזלנותא
Raba holdsthat he is disqualified prospectively [only]: now, the entire law of a falsified witness isanomalous; for [it is two against two, then] why accept the evidence of one pair rather than that ofthe other? Therefore it can take effect only from the time that this anomalous procedure isemployed. Some say that Raba really agrees with Abaye; yet why does he rule [that the incompetenceis] prospective? — Because of the purchaser's loss.<span class="x" onmousemove="('comment',' If purchasers have transacted business through documents signed by the Zomemim, having been unaware of their disqualification, they would become involved in considerable loss, should their evidence be declared invalid. ');"><sup>5</sup></span>