The 93rd mitzvah is that the Nazirite is commanded to cut his hair and offer sacrifices at the conclusion of his Nazirite period.
In the words of the Sifra: "There are three cases in which haircutting is a mitzvah — the Nazirite, the leper, and the Levite." The haircutting of the Levites only took place in the desert1 and is not a commandment for all generations [and is therefore not counted among the count of 613].2 The haircutting of the Nazirite and the leper, however, apply to all generations [and therefore are counted among the 613].
It is clear that there are two categories of haircutting for a Nazirite. One is in a case where he became tameh, as the verse says,3 "If a person dies in his presence suddenly...[when he purifies himself on the seventh day, he must shave off the hair on his head]."
The second category is cutting his hair while he is in a state of purity, as the verse says,4 "[This is the law of what the Nazirite must do] when the term of his Nazirite vow is complete."
These two haircuttings do not count as two separate mitzvos, since the first one is included in the general requirement upon the Nazirite to allow his hair to grow when he is in a state of holiness, as explained above.5 The verses then elaborates upon this mitzvah [of letting the hair grow], saying that should he become tameh during his Nazirite period, he must cut his hair and bring offerings. He must then resume once again growing his hair in a state of holiness for the complete duration of his vow.6
This case is similar to the two haircuttings of the leper which also count as one mitzvah, as explained there.7
Later,8 I will explain why the haircutting of the Nazirite and the sacrifices9 he brings are counted as just one mitzvah, although the haircutting of the leper and his sacrifices are counted as separate mitzvos.
The details of the mitzvah regarding the Nazirite's haircutting are explained in tractate Nazir.
