Halakhah su I Samuele 4:23

From the laws of the commandment is that which they, may their memory be blessed, said (Mishneh Torah, Laws of Vessels of the Sanctuary and Those who Serve Therein 4:11) that each and every shift would have an appointed man - and he was the head of all of the men of the shift. And he would divide them into households. And on each and every day of the days of the week, the heads of the households would distribute [the jobs, assigning] men to the work, each man his work. And they would change the shifts from one Shabbat day to the next Shabbat day, and rotate accordingly.