Shoftim: 18, 6-8 Mishmaros The Torah is fixed and unchanging, but some things didn’t begin right away they took time to develop and achieve a permanence and when that time came their permanence was like all other ideas in Torah that they never change. One of those things are the Mishmaros: the division of Kohanim into 24 families who worked in the Beis HaMikdash intermittently. This wouldn’t fully manifest until the times of Shmuel and Dovid. The Possuk describes the process of creating the Mishmaros as a sale: the Kohanim sell the rights to constant work in (and access to) the Beis HaMikdash by selling (23 weeks) to the other Kohanim to keep the rights to one week for their family. The exceptions to this rule are: 1) Yamim Tovim, when all Kohanim share the rights to the Beis HaMikdash together, 2) Personal Korbanos any Kohen can bring at any time. A suggested explanation for all this.
