One of the most basic requirements of nedarim – becoming obligated by making a vow – is that the person have clear intent; he must express himself in a clear manner. This is true not only for nedarim in general, but for nezirut as well. Nevertheless, as our Mishna makes clear, there is no set formula for taking on nezirut. Substitutes (referred to by the Mishna as kinuyei nezirut) or intimations (referred to by the Gemara as yadot nezirut) also create a full obligation.
The Gemara on our daf discusses the order in which kinuyei nezirut and yadot nezirut are presented by the Mishna and suggests that kinuyei nezirut are mentioned first because they are mi-d’oraita (from the Torah), while yadot nezirut, which are learned mi-derasha (derived from a homiletic teaching) are taught afterwards.
Tosafot point out that, according to the Talmud Yerushalmi, kinuyei nezirut are expressions developed by the Sages for use when making vows, and that effectively both kinuyei nezirut and yadot nezirut are of rabbinic origin. Based on this approach, even though the Gemara finds passages in the Torah to which the concept of kinuyei nedarim is connected, someone who uses such an expression to accept nezirut upon himself would not bring the sacrifices that a nazir ordinarily brings, even though he will receive malkot – punishment of lashes – if he breaks the rules of nezirut, albeit only on a rabbinic level.
Some commentaries suggest that, according to our Gemara, both kinuyei nezirut and yadot nezirut are treated as creating biblical obligations. According to this approach, when our Gemara presented yadot nedarim as being derived mi-derasha, it does not indicate that yadot are rabbinic, but rather that they are not clearly written in the Torah. This approach is similar to that of the Rambam, who uses the expression mi-divrei soferim (“from the words of the scribes”) when referring to laws that have biblical weight but are derived from the words of the Torah rather than being written explicitly there.