Keritot 17 - The Offering Of Uncertainty
An offering of uncertainty arises in the cases where one is not sure if he transgressed or not. It suspends his judgment until he is able to clarify the situation, and then he either brings a sin offering or nothing at all.
For example, if one had in front of him two pieces of fat, and he thought that he was eating permitted fat, "shuman", but later became aware that it might have been forbidden fat, "chelev." Another possibility: his wife and his sister were with him in the house, and he cohabited with one of them, thinking, of course, that it was his wife, and later it transpired that it might have been his sister. Yet another case: Sabbath or weekday. He did labor at the end of Sabbath thinking that it was already weekday, but later found out that it may have been Sabbath. In all these cases one brings the offering of uncertainty.
In the ruling there always were two choices. Rav Assi, however, said that even if he ate one piece of meat, but it could have been permitted or prohibited, he brings a sacrifice. What is the reason of Rav Assi? - The Torah has written "Mitzvat" - a mitzva, so it applies even in the case of one, and the written word of the Torah is paramount. Chiya bar Rav said that there has to be a choice between two alternative, since this word is read "Miztvot", in plural, and pronunciation is more important than the spelling.
Art: Francis Hayman - George Rogers with his Wife Margaret and his Sister Margaret Rogers