The Mishna on our daf teaches that when a signed document that needs to be authenticated, under certain circumstances the original witnesses who are brought in can say “yes, they are our signatures, but…
- …anusim hayinu – we were coerced” (and it was untrue)
- …ketanim hayinu – at the time we were minors” (who cannot testify) or
- …pesulim hayinu – we were disqualified witnesses.”
In these cases, they are believed only if there is no other corroboration of their signatures. If, however, there are other witnesses who can attest to the veracity of their signatures, or if there are other documents that included their signatures to which this can be compared, then we do not believe them.
The reason the witnesses can renounce their original testimony is explained by the Gemara to be based on the rule, “Ha-peh she-asar hu ha-peh she-hitir – the mouth that forbade is the mouth that permitted.” This means that since we can only uphold the document based on their say-so, they are granted a higher level of believability with regard to their own statement. If the document can be authenticated in another way, then they do not gain that trust, and we accept the testimony as it appears in the document.
It is clear that for us to believe them, the original witnesses’ arguments explaining why their earlier testimony should not be accepted must be convincing. If they explained that they were underage at that time or that their lives were threatened, we can well understand why their original testimony should be voided. With regard to the claim pesulim hayinu we find a number of explanations.
Rashi offers two approaches – either that they were close relatives who cannot testify or they were mesahek be-kubiya – they were dice players – and gamblers cannot testify.
The Ramban argues that Rashi was well aware of that limitation, which is why he chooses specifically the case of mesahek be-kubiya. Unlike real cases of evil-doing where the rule of ein adam meisim atzmo rasha applies, according to the Gemara in Massekhet Sanhedrin a mesahek be-kubiya cannot testify because he is eino osek be-yishuvo shel olam – he is not engaged in productive activities in the world, which is a severe criticism, but it is not an admission of evil-doing.