Sefer HaChinuch ספר החינוך

The commandment of the service of the Levites in the Temple: That the Levites serve in the Temple to be gatekeepers and to sing everyday over the sacrifice, as it is stated (Numbers 18:23), “And the Levite shall serve, he, etc.” And the language of the Sifrei is “I might understand [it to mean:] if he wants, he serves, and if he does not want, he does not serve. [Hence], we learn to say, ‘And the Levite shall serve, he’ — [even] against his will,” meaning to say that this thing is an obligation, and that this matter is incumbent upon him perforce. And it is also elucidated in the second chapter of Arakhin 11a, that no one should ever say the song of the mouth (in the Temple) besides the Levite. And this commandment is repeated in the Torah with a different expression, as it is stated (Deuteronomy 18:7), “And he shall serve in the name of the Lord, his God.” And they said there in Arakhin, “What is the service that is [done] in the name of the Lord? It should be said, it is song.”

It is from the roots of the roots of the commandment [that it is] because it is the glory of the King and the place that there be specific people from a specific tribe, that are affixed to His service, and that foreigners not come to serve. [It is] similar to earthly monarchy, [wherein] they appoint specific respected people, such that all of the work of the king be done through them. As it is not fitting for a king that his servants in front of him should change every day, and that all would make use of the crown of the king’s service. That is something clear.

From the laws of the commandment is that which they, may their memory be blessed, said (Bekhorot 30b), that we do not accept a [Levite] who accepts all of the commandments of the Levites except for one thing, [but rather only if] he accepts all of them. And their service was that they would be guardsmen for the Temple, as we have written in this Order (Sefer HaChinukh 388). And some of them were gatekeepers, to open and close the gates of the Temple.

But the core of their service is to sing over the sacrifice. And they would only say song with communal burnt-offerings that are obligatory and upon the peace-offerings of [Shavuot] at the time of the wine libation; but not over voluntary offerings that the community would make for the “end of the altar.” And so [too], they would not say song upon libations that came on their own. A Levite who is bereaved (onen) is permitted to serve and sing. We do not ever decrease below twelve Levites that stand on the platform to say song over the sacrifice, but we [may] increase [as much as is wanted]. And the song that the Levites would say was with the mouth, as the crux of song is with the mouth. And others would stand there that would play musical instruments — some of them Levites and some of them pedigreed Israelites that [their family be permitted to] be married to [priests] — as only the pedigreed are ever able to go up to the platform. And we never reduce below nine lyres, but we [may] increase [as much as is wanted]. And there was only one cymbal. And it appears that the reason is that the sound of cymbals is loud and a bit frightening; and [so] if there were many, the rest of the musical instruments that were there would not be heard — all the more so, the song of the mouth. And the hollow of the flutes that they would play with were of reed, since their sound is pleasant. And the flute would strike [play] in front of the altar twelve days a year. And it pushes off the Shabbat, since it is [a part of] the service of the sacrifice, and the sacrifice pushes off the Shabbat. And a [Levite] does not come to the service until they teach him for five years. And as they, may their memory be blessed, learned from the verse. And from here, they, may their memory be blessed, said (Chullin 24a) that a student that does not see a good sign of (some success) for five years, will never see [it]. And he does not ever come to serve until he is an adult, as it is stated (Numbers 4:49), “each man to his service.” But a Levite is not disqualified by age and not by blemishes, but rather by deterioration of the voice, such as the old men whose voices deteriorate at the time of old age. And that which is stated in the Torah (Numbers 8:25), “But at the age of fifty they shall retire from the legion of service” is only at the time they were carrying the tabernacle from place to place. And even at the time of old age when his voice deteriorates, he is not disqualified from guarding the Temple and from closing the doors. And all of this and the rest of its details are nicely elucidated in [various] places in Tamid and Middot; also some of this matter is elucidated in the second chapter of Arakhin. And I have written a little at length about this for you, my son, as the Temple will soon be built, and you will need it. Amen, so should God do. (See Mishneh Torah, Laws of Vessels of the Sanctuary and Those Who Serve Therein 9.)

And [it] is practiced at the time of the [Temple] by the Levites. And a Levite that transgresses it and did not sing over the sacrifice on his set day — as they had set days, according to the division of the shifts — but rather was silent, has violated this positive commandment. And his punishment is very great, as he appears as if he does not desire the glory of the service of God; and therefore God will prevent him from [any other] glory. But the one of the Levites who desires the service of his Creator; with him will be life, peace and blessing.