Rav Shmuel quotes Rabbi Yoḥanan as teaching that if a woman has a fixed menstrual cycle, her husband can figure the day when she is ritually pure and they can engage in relations – even if she does not tell him that she has already immersed in the mikva. This ruling leads to a general discussion about the relationship between safek – an uncertain situation – and vadai – a firm reality. Will a possible change in status (e.g. immersion in a mikva) allow us to assume that the reality (that the woman was a nidda) has changed?
One of the cases that is brought to help clarify this issue is the following:
There was an incident involving the maidservant of a certain olive gatherer in the city of Rimon, who cast a non-viable newborn into a pit, and a priest came and looked into the pit to ascertain whether it was male or female. The incident came before the Sages and they deemed the priest ritually pure due to the fact that ḥulda and bardelas are commonly found there.
In this case it is clear that even though we know for certain that the dead body was in the pit, the kohen remains ritually clean since one of these animals is likely to have removed it.
The word ḥulda is used in modern Hebrew to refer to a rat. However, the animal referenced in the Talmud is a predator, and the only rat in the region at the time was the black rat which is not predatory. This animal is more likely a marten, a member of the weasel family found in Israel that fits the various descriptions associated with the ḥulda in other places in the Talmud.
From its appearance in different places in the Talmud, there are three different creatures that are referred to as a bardelas: a leopard (a similar Greek term denotes spots), a cheetah (called by this name during the mishnaic era), and a hyena. Given the description that the animal feeds on carrion and does not avoid humans, it is most likely the term here refers to the hyena.