2,641. How One Is Liable for an Unintentional Oath

Hilchos Shevuos 3:7

Given our definition of an unintentional oath (in the previous halacha), one might ask what’s an unintentional oath of expression regarding the past for which one would be liable to bring a variable guilt offering. The answer is if someone took an oath that he didn’t eat and he knew that he had eaten, plus he knew that making such a false oath is prohibited, but he didn’t know that he would be liable to bring an offering because of it. This is the case of an unintentional oath of expression regarding the past for which one would be liable to bring a variable guilt offering.

Hilchos Shevuos 3:8

An example of an unintentional oath of expression regarding the future for which one would be liable to bring a variable guilt offering is if someone took an oath not to eat bread made from wheat, he forgot and thought that he had taken an oath to eat bread from wheat, and he did so. In this case, he became unaware of the oath’s details even though he remembered the subject of the oath. This is an unintentional oath of expression regarding the future for which one would be liable to bring an offering.