Chapter 13! With the new mishnah, and a focus on oaths regarding grain-offerings. What happens when one takes an oath, but isn't sure what amount he'd specified in his oath. That is, how to cover the oath by a "maximum" of the grain-offering (or all of them, as the case may be). Also, who taught that one might need to bring all of them? The Gemara approaches this question by a process of elimination, almost, establishing first who did not subscribe to this view, before concluding whose view it was. With parallels drawn from the Nazir and the person recovering from tzara'at. Is Rabbi Shimon's view dependent on his allowing sacrifices to be brought conditionally?