In ancient times, not everyone took the laws of purity as seriously as the rabbis did. So the rabbis developed rules about who they could trust and who they couldn’t.
On yesterday’s daf, we learned that potters in the environs of Jerusalem are trusted about the purity of their pots, but those who live at a distance are not. This is because sacrificial foods are associated with the Temple in Jerusalem, so it makes sense that potters in the area would take care to maintain the purity of their wares so they could be used for Temple purposes. Failure to do so would be bad for business. A Jerusalem craftsperson with a shady record on ritual purity would lose a lot of business during the busy pilgrimage festival season, and perhaps year round.
While some may question the credibility of shopkeepers when a potential sale is at hand, a mishnah on today’s daf speaks to the credibility of a shadier group of people:
Thieves who returned the vessels they had stolen are deemed credible when they say: We did not touch the rest of the objects in the house, and those items remain pure.
According to this mishnah, if a thief, while returning a stolen item, claims not to have touched other objects as the theft was in progress, they are trusted. On their word alone, the purity of items remaining in the house is determined.
But why should we trust thieves? Doesn’t the fact that they are criminals make them untrustworthy? The Gemara cites a mishnah (Tahorot 7:6) which suggests that they are.
Concerning the thieves who entered a house, only the place where the feet of the thieves had trodden is impure.
According to this text, all vessels that are found in the part of the house that the thieves entered are automatically impure — regardless of what the thief says. This implies that the thief is not a credible source regarding which items in a robbed home are impure and which are not.
So are thieves to be trusted about matters of purity or not? Which mishnah do we follow? Well, as it turns out, it depends.
According to a teaching from Rav Pinhas in the name of Rav, the mishnah on our daf is dealing with a case where the thieves repented, which is why they are deemed credible. The mishnah in Tahorot is referring to a case in which the thieves did not repent and are therefore not deemed credible.
So thieves, in general, are not to be trusted about matters of ritual purity. But when they are repentant and make restitution for their acts of thievery, we can trust them to help us determine the purity status of items they left behind.
Read all of Chagigah 26 on Sefaria.