David and Zadok divided them (vayyeḥaleqem) etc. The yod has a segol and the ḥet has a qameṣ; but this is just like vayyaḥalqem, with a pataḥ. The same is true for “vayyeḥalqem David” above (23:6), for they have the identical vocalization. I have already provided the philological explanation of this in the Mikhlol (35b). What this means is that David changed the shifts from their prior alignment. For there were originally eight from the family of Eleazar and eight from the family of Ithamar. But David saw that the male heads among the descendants of Eleazar were more numerous than those of Ithamar (v. 4). So he took with him one representative from Eleazar and another from Ithamar, and he added eight shifts. He thus established twenty-four shifts, sixteen from Eleazar and eight from Ithamar (ibid.). This, then, is the meaning of “there was a onefold increase in what was held by clans of Eleazar” (v. 6)—meaning above what had been beforehand—and “whatever Ithamar held they held” (ibid.)—meaning that what Ithamar had held beforehand they held at this point also, because no shifts were added to theirs. There is the following debate among our Sages, of blessed memory (b. Taanit 27a). Some of them say that Moses instituted eight shifts, four from the family of Eleazar and four from the family of Ithamar; that Samuel then came and realigned them into sixteen, eight from Eleazar and eight from Ithamar; and that David came and realigned them into twenty-four. And some of them say that Moses instituted sixteen, eight from Eleazar and eight from Ithamar, and that Samuel and David came and realigned them into twenty-four, as it says, “David and Samuel the seer established that they be set up like this” (1 Chr 9:22).

They divided them by lot, the one group together with the other. This means that [David] gave no preference to one over the other, because they were all Sanctuary officers and officers of God—the sons of Eleazar and the sons of Ithamar. Thus, they followed whatever the lottery determined: he gave no preference to any one over another, except in the case of the high priesthood, which belonged to the descendants of Eleazar, as we have explained above (5:27). Shemaiah son of Nethanel, the scribe, wrote down twenty-four shifts and [the names of] the male heads, put them into an urn for drawing lots, and the first lot fell on Jehoiarib ….

Avot the head opposite his younger kinsman. That was his name—Avot (=Avoth). “Opposite his younger kinsman” means that an older one did not take precedence over a younger one. Rather, [the Levites] too would draw lots among themselves, just as did the priests: both old and young followed whatever the lottery determined. Accordingly, it says “young and old alike, the wise one with the student” (1 Chr 25:8), the wise one meaning the older one and the student meaning the younger one.