Sefer HaChinuch ספר החינוך

That the priests not be involved in the service of the Levites and the Levites in the service of the priests: That the Levites not be involved in the service of the priests and the priests in the business of the Levites, but rather each one does the work designated for him, from that which is written (Numbers 4:19), “each man to his service and his load.” And the language of the prevention that comes about this is that which is stated about the Levites (Numbers 18:3), “but to the vessels of the Holy and to the Altar they shall not approach”; and afterwards the verse returns to speak about the priests, “and they shall not die, also they and also you” — meaning to say with this that you too, you are included in this negative commandment. Since just like the Levites are prevented from their work [when it is not assigned to them], so too are you prevented from your work [when it is not assigned to you]. And the language of the Sifrei on Numbers 18:3: “‘To the vessels of the Holy and to the Altar’ [is the] warning; ‘and they shall not die’ is the punishment. I only [know] that the Levites are punished and warned about the service of the priests; from where do I know [the same] about the priests [doing] the service of the Levites? [Hence] we learn to say, ‘also you.’” And we have found (Sifrei on Numbers 18:3) that Rabbi Yehoshua ben Chananiah wanted to help Rabbi Yochanan ben Gudgodah in the closing of the doors, [and] he said to him, “Go back, as you are already liable with your soul (life), as I am from the gatesmen and you are from the singers.” Behold, it is elucidated that any Levite that does work in the Temple that is not his designated work is liable for death by the hand of the Heavens. And so [too,] the priests are warned not to approach the work of the Levites. However, if they did transgress this, they are not killed, but rather [get] lashes. And they said in the Mekhilta (Sifra Zuta), “‘To the vessels of the Holy and to the Altar they shall not approach.’ It is possible that they would be liable if they touched [them]. [Hence] we learn to say, ‘but’ — for the work they are liable, and not for touching. I only [know] about the Levites for the [work of the] priests, from where do I know about the priests for the [work of the] Levites? [Hence] we learn to say, ‘also you.’” And there it is said that the Levites on that of the priests is [punished] with death, but the priests on that of the Levites is only with [the consequences of violating] a negative commandment.

It is from the roots of the commandment [that] because the service of these two groups is a very precious and holy service, therefore the work needs to be very guarded from abandon, from slothfulness and from forgetfulness. And there is no doubt that there is more negligence with any work incumbent upon two people or more, than work incumbent upon one alone. As many times each one of the two of them will rely upon his fellow, and the work will be neglected by both of them. This is something clear to all men. And by way of a parable, they, may their memory be blessed, said about something similar to this (Bava Batra 24b), “A stew of partners is not hot and not cold.”

From the laws of the commandment [is] that which they, may their memory be blessed, said (Mishnah Shekalim 5:1), “There were fifteen appointees in the Temple: one was over the times,” meaning to say to determine the time of the sacrifice. And he immediately envigorates them and says, “Priests, stand at your services; Levites, to the platform; and Israel, to serve!” And once they hear his voice, each one comes to his work. And specific priests and Levites would serve there. And it is like they, may their memory be blessed, said that Moshe and Shmuel the Seer and King David divided them into twenty-four shifts, as it is found in Taanit 27a. And each shift would serve for a week and take turns in a cycle. And the head of the shift would divide all the men of the shift into clans. And each day of the week specific men would work, and the heads of the clans would divide specific men, each one to his service, and they would not be allowed to assist one another [in their tasks]. And so [too,] the Levites, the singer would not be allowed to help the gatekeeper; nor the gatekeeper, the singer. And of these fifteen appointees that we mentioned, we have already said that the first was appointed over the times; the second was appointed over the closing of the gates; third over the guards; fourth over the singers, etc., as it comes in the Mishnah. [This] and the rest of its details are in [various] places in the Order of Kedoshim and in Sifrei and in Mekhilta, as we have said above. (See Mishneh Torah, Laws of Vessels of the Sanctuary and Those Who Serve Therein 3).

And it is practiced at the time of the [Temple] by priests and Levites. And a Levite that transgresses it and does the work of the priest in the Temple, or even the work of his fellow Levite, is liable for death by the hand of the Heavens. And so [too,] a priest that transgressed and did the work of the Levite has violated a negative commandment, but he is not liable for death, as we said above. And apparently, a priest that assists in the work of a fellow priest is also [liable for] death.