Comentario sobre Deuteronómio 18:8

חלק כחלק יאכלו THEY SHALL ENJOY LIKE PORTIONS — This teaches that they (the priests who come to Jerusalem on the festivals as pilgrims but are not in charge) participate in the hides (of the burnt offerings due on the festivals) and the flesh of the he goats brought as sin-offerings on account of the festivals. One might think that they participate also in sacrifices which are offered not on account of the festivals, as, for instance, the continual burnt offerings, the additional offerings due on account of Sabbath (on which a festival happens to fall) and vow- and free-will offerings! Scripture, however, states: לבד ממכריו על האבות [THEY SHALL ENJOY LIKE PORTIONS] EXCEPT THE SALE OF THE FATHERS — i.e. except those things which their ancestors sold to each other in the days of David and Samuel when the system of shifts was established and they made, as it were, an agreement of sale, saying, “Take thou the ordinary priestly perquisites during thy week and I shall take them during my week (Sifrei Devarim 169:3; Sukkah 56a).

לבד ממכריו אל האבות, the members of any priestly roster, known as בית אבות or as here. plain אבות, do not have the right to share their sacrificial meat with their relatives or friends except when this meat was part of the daily or weekly public offerings. These may be shared or exchanged between different rosters. However, any offerings brought to the altar on the pilgrimage festivals are not subject to the authority of the priestly roster officiating during that week at all. The expression ממכריו, “of his acquaintances,” does not apply to the days of the festivals. Therefore, the Torah orders that on that occasion basically any priest present may eat a share of such offerings regardless of whether he belongs to the roster of that particular week. This is why the Torah writes; חלק כחלק יאכלו, of the offerings presented during the festivals all the priests enjoy an equal share.

לבד ממכריו על האבות, according to the plain meaning: “like one of his personal acquaintances if he has such among the priests serving in the Temple, who is willing to appoint him to offer his personal sacrifice on his behalf so that he will be able to eat some of the sacrificial meat with him, and the restriction of his not being part of the day’s roster would be waived.” (compare Sukkah 56)