The Gemara continues its discussion of the halakha of a zaken mamre – an elder Sage who rebels against the decision of the Sanhedrin. Under what circumstances will a zaken mamre be liable to receive a death penalty for his rulings? According to the Mishna on today’s daf the situation that would lead to death is very limited.
The Mishna teaches that for the law of zaken mamre, if the Sage teaches that people should reject a biblical law, he is not considered to be a zaken mamre, since no one will take seriously a ruling that negates a law that is clearly written in the Torah. It is only if he rejects the rabbinic interpretation of a Torah law – what the Mishna refers to as divrei soferim – that he will get that status. The example given by the Mishna is the case of tefillin. If he teaches that tefillin should not be worn, he will not be considered a zaken mamre, since that is a law that is clearly taught in the Torah in a number of places (see 13:9, 16; 6:8 and 11:18). If, however, he rejects the rabbinic understanding that there are four totafot – “frontlets” – containing four sections of the Torah, and he rules that there must be five, then he will be considered a zaken mamre.
In the Gemara we find Rabbi Elazar quoting Rabbi Oshaya as teaching that the only case where someone can become a zaken mamre is a situation where the source of the law is biblical and its details are interpreted by the Sages – divrei soferim – and that adding to their interpretation would ruin the mitzva. Furthermore, the only case where such a situation is found is with regard to tefillin. In response to the Gemara’s question that even if a fifth section was added, perhaps we should view it as an irrelevant addition and focus only on the four sections that make up the tefillin, Rabbi Zeira’s teaching is quoted: If the outer section of the tefillin is covered and is not exposed to the air, then the tefillin are pasul – they are disqualified.