Shevuos 2:5-3:1

Shevuos 2:5

Rabbi Eliezer cites Leviticus 5:2, which says “a creeping thing” and “it is concealed from him” – one is liable if a creeping thing is concealed from him (i.e., he forgot about the impurity) but one is not liable if the Temple is concealed from him (i.e., he forgot where he was). Rabbi Akiva cites the same verse, “it is concealed from him that he is unclean” – one is liable if it is concealed from him that he is unclean but one is not liable if it is concealed from him that he’s in the Temple. (The difference between the opinions of Rabbi Eliezer and Rabbi Akiva involve a case where one knows that he is impure but not the source of it – see Talmud Shevuos 18b.) Rabbi Yishmael says that the Torah repeats “it is concealed from him” in order to render a person liable for both forgetting his ritual impurity and forgetting that he’s in the Temple.

Shevuos 3:1

There are two oaths that are four, as follows: if a person swears to eat or not to eat, that he did or did not eat. If he swears not to eat, he is liable for eating even the smallest amount; this is the opinion of Rabbi Akiva. The Sages asked Rabbi Akiva where we see a precedent that a person is liable for eating even the smallest amount. Rabbi Akiva replied that there’s also no precedent that a person becomes obligated to bring an offering just for speaking, which is the case with oaths. If a person swore not to eat and he both ate and drank, he is only liable for violating one oath. If he swore not to eat and not to drink, and then he ate and drank, he is liable for violating two oaths.