The ninth perek of Massekhet Nedarim deals with the various ways that a neder can be annulled by a Jewish court or by a hakham. One of the methods used by the court is a petah that the rabbi might find by suggesting that the individual who made the neder may not have been aware of some mitigating circumstance when he took the vow. If he admits that with that knowledge he would never have vowed, the hakham can declare the vow to have been taken in error and declare it null and void.
One of the questions addressed here is whether a situation that is nolad – one that did not exist at the time that the neder was made – can be used as a petah. For example, can a person who vows that he will derive no benefit from a certain individual ask to have the neder annulled if it turns out that he becomes a sofer? In such a case we find a dispute between Rabbi Eliezer and the Hakhamim. Rabbi Eliezer believes that nolad can be used as a petah, while the Hakhamim rule that it cannot.
The term sofer is used in the Gemara in a number of different ways. One meaning of sofer is a Torah scholar who is knowledgeable in the books of the Torah, as we find in the title carried by Ezra HaSofer. The Sages borrow this term when they refer to their own works, calling rabbinic ordinances divrei soferim. According to this definition, the argument of the man who took the vow was that he would not have wanted to distance himself from a person who became a Torah scholar, particularly because the scholar was sought after in the community.
Another usage of sofer is to indicate a person’s profession as a scribe. Aside from writing tefillin or mezuzot, a scribe also wrote deeds, contracts, etc. for the court or for individuals. As such, it is likely that the person who took the vow may need his services at some point.
Finally, a sofer might be the title of someone who teaches children. In any case, it would be commonplace for a person to need the services of a sofer.