R’ Yochanan and Reish Lakish dispute the definition of an “unwitting” sinner. Is it enough that he is unaware of the punishment even if he knows that a labor is forbidden on Shabbos? Defining kares, excision, the punishment for intentional violation of a prohibition vs. bringing a chatas, sin-offering, for unwitting violation of that prohibition. What if I’m walking in the desert and lose track of the day of the week? Rav Huna and Hiyya bar Rav disagree whether one counts six days and then observes Shabbos or vice versa. Rava adds that he should prepare food one day at a time though this means he will cook food on the actual Shabbos and the one he has designated.