The Torah commands in Parashat Korah (Bamidbar 18:23), “Ve’abad Ha’Levi Hu Et Abodat Ohel Mo’ed” – that the Leviyim must perform special tasks in the Bet Ha’mikdash. Specifically, the Leviyim served as the gatekeepers, and sang in the choir whose music accompanied the offering of certain sacrifices.
The Sefer Ha’hinuch writes that the Torah commanded the Leviyim to serve these roles just as a mortal king has especially hired staff to perform various jobs in his palace. It would be disrespectful, the Sefer Ha’hinuch writes, to repeatedly hire different people for the various jobs that were needed in the Bet Ha’mikdash, and so the Torah designated the tribe of Levi as the “staff” assigned over the various jobs in G-d’s “palace.”
If a Levi accepts upon himself the responsibilities of the Leviyim except for one certain task, he is not permitted to perform any of the jobs until he proclaims his willingness to do all the tasks assigned to the Leviyim.
A Levi is allowed to perform his duties in the Bet Ha’mikdash in a state of Aninut – meaning, after the death of an immediate family member, before the burial.
The choir of Leviyim would sing during the offering of public Ola sacrifices – including the daily Tamid sacrifice – as well as during the pouring of the wine on the altar on Shabuot. No fewer than twelve Leviyim would sing in the choir. Although the role of singing is assigned exclusively to the Leviyim, the playing of musical instruments which accompanied the singing could be done even by Yisraelim. The orchestra that played the instruments consisted of at least nine violins and one set of cymbals (presumably, because the cymbals are very loud, and thus more than one set of cymbals would produce too much noise). On twelve occasions during the year, a flute was added – during the offering of the Korban Pesach on the 14th of Nissan, on the first day of Pesach, during the offering of Pesach Sheni on the 14th of Iyar, on Shabuot, and on each of the eight days of Sukkot. The flute is to be played even when these occasions fall on Shabbat.
A Levi does not join the choir until he has undergone five years of training. The Sages infer from this Halacha that if a student does not succeed in his Torah learning after five years, then it can be presumed that he will not succeed thereafter.
Whereas Kohanim become disqualified from performing their duties in the Bet Ha’mikdash if they develop a physical blemish, this is not true of Leviyim; a Levi with a physical blemish may perform his duties. A Levi likewise does not become disqualified when he reaches old age. Although the Torah says that a Levi serves only until the age of 50, this applied only to the Leviyim’s service in the Mishkan; in the Bet Ha’mikdash, Leviyim may serve even beyond the age of 50. A Levi becomes disqualified from serving in the choir once his voice is not strong enough to sing properly, at which point he leaves the choir and becomes a gatekeeper.
In concluding his discussion of this Misva, the Sefer Ha’hinuch – who wrote this book for his son – explains to his son that he elaborated on this Misva because the Bet Ha’mikdash will, hopefully, soon be rebuilt, whereupon “you will need” to know this information. Meaning, the author of the Sefer Ha’hinuch was a Levi, and thus expressed to his son the hope that they would soon have the privilege of fulfilling this Misva in the Bet Ha’mikdash. Likewise, in the introduction to this work, the author – who never says his name – identifies himself as “a Jewish man from the house of Levi, a Barcelonan,” clearly stating that he was a Levi. Indeed, some have suggested that the author was the Ra’a – Rav Aharon Ha’levi (13th century), who was a Levi.
A Levi who refuses to preform his duties in the Bet Ha’mikdash is in violation of this affirmative command, and the Sefer Ha’hinuch warns that he is deserving of harsh punishment for giving the impression that he has no interest in serving G-d.