The third perek of Massekhet Nazir that begins on today’s daf deals with issues having to do with the exact length of time of nezirut and when it ends. The complications occur less in cases of simple nezirut and more often in situations where two or more instances of nezirut occur one after another, or where the nezirut is interrupted if the nazir becomes tameh.
As we have learned, the standard length of nezirut is 30 days. While this is ideally kept as thirty full days, if someone cut his hair on the thirtieth day, we view him as having fulfilled his obligation (this is either because, biblically, the obligation is only 29 days, or because we apply the rule of miktzat ha-yom ke-kulo – we count part of the day as a full day – see the opinions of Rav Mattana and bar Pada on daf 5). What happens when a person accepts two consecutive neziruyot? Can the thirtieth day count as both the last day of one nezirut and the first day of another?
With regard to the nazir who becomes tameh, the rule is clearly stated in the Torah that tum’ah “undoes” the days that have been kept and the nezirut must begin anew. What if a person has completed the days of his nezirut but becomes tameh before bringing the sacrifices that indicate the end of his nezirut? Must he begin his nezirut over again, or can we view the nezirut as having been fulfilled?
The Mishna on our daf raises the case of a person who accepts nezirut upon himself while standing in a cemetery. The Gemara quotes Reish Lakish as ruling that no nezirut can take effect in such a case, and even when he leaves the cemetery he will not become a nazir unless he repeats his desire to do so. Rabbi Yohanan argues that the nezirut will take effect. Not only does he become a nazir as soon as he becomes tahor (ritually pure), but even while in the cemetery he is not allowed to drink wine or cut his hair.