Musar zu Schemot 2:21

Keeping this in mind, we can understand a peculiarity in 18,6. There the Torah writes: "When the Levite who lives in one of your gates (towns) comes to the place G–d has chosen, he may do so whenever he pleases. He may serve in the name of his G–d like all his fellow-Levites who are in attendance there." The obvious question here is why, in describing the function of the priest, the Torah in this paragraph merely calls him: "the Levite," while in the preceding paragraph (18,3-5), it calls him by his rightful title? The appointment of the priest as a כהן, originated in the emanation חסד, as opposed to the appointment of the Levite as a tribe with special functions, which originated in the emanation גבורה. Because the priest is on a more elevated level than the mere Levite, his conduct is measured by a more exacting yardstick. The Torah alludes to this in verse 6 where the priest is reminded that he is basically judged as a Levite, i.e. by the standards of the emanation גבורה, otherwise known as מדת הדין, the attribute of Justice. The allegorical meaning of the words חלק כחלק יאכלון in 18,8 is that on the holidays, when all of the priests are allowed to eat a share of the sacrifices being offered, they all share the same standards. We know that the world is judged (Rosh Hashanah 16a) on the three festivals Passover, Pentecost and Tabernacles in addition to New Year's when people's lives are in the balance. On Passover the size and quality of the forthcoming grain harvest is decided upon in Heaven; G–d decides on the size and quality of the yield of fruit-bearing trees on the Festival of Weeks, and on the water supply during the rainy season on the Festival of Tabernacles. These decisions are made by the attribute of Justice. The priests are to remind themselves of the activities of the attribute of Justice when they partake of the offerings on these festivals.