Numbers 4 begins the discussion of the jobs of the Levites when the Mishkan would travel from place to place. Each of the three families– Gershon, Kehat, and Merari were responsible for a different part of the Mishkan. The chapter first discusses the family of Kehat. They were responsible for carrying the vessels in the Mishkan. There was something unique about their job. While Gershon and Merari could take apart the Mishkan and the curtains themselves, Kehat needed help from the Kohanim. The Kohanim would first have to enter the sanctuary and cover up all the vessels properly and then Kehat would come in and set them up to travel.
“When Aaron and his sons have finished covering the sacred objects and all the furnishings of the sacred objects at the breaking of camp, only then shall the Kohathites come and lift them, so that they do not come in contact with the sacred objects and die. These things in the Tent of Meeting shall be the porterage of the Kohathites” (verse 15).
וְכִלּוּ אַהֲרֹן וּבָנָיו לְכַסּוֹת אֶת־הַקֹּדֶשׁ וְאֵת כָּל־כְּלֵי הַקֹּדֶשׁ בִּנְסֹעַ הַמַּחֲנֶה וְאַחֲרֵי־כֵן יָבֹאוּ בְנֵי קְהָת לָשֵׂת וְלֹא יִגְּעוּ אֶל־הַקֹּדֶשׁ וָמֵתוּ אֵלֶּה מַשָּׂא בְנֵי־קְהָת בְּאֹהֶל מוֹעֵד.
At first this seems like a nice partnership. Because the Kohanim would have daily contact with the vessels and the Levites did not, the Kohanim should protect the Levites from coming into contact with the holy vessels. At the same time, however, the job of the Levites was to carry and transfer the Mishkan. Ancient Near Eastern cultures often had priestly hierarchies as well: in Ancient Egypt, only the highest priests could enter the inner sanctuaries while lower priests and temple workers served in graded roles beneath them; in Mesopotamia, chief priests oversaw ritual priests while lower-ranking personnel handled support and administrative duties; in Hittite religion, elite or royal priests stood at the top of a system supported by specialized ritual staff; and in Ugarit, senior priests performed offerings with junior personnel assisting in preparation and maintenance. But the manual labor of the Kohanim is unique. Why would the Kohanim, who had a higher job responsibility be troubled with the manual labor of packing up the Mishkin? Perhaps this set up had more to do with an incident in the past. Verse 15 specifically mentions that the kohanim had to cover up the sacred objects. When else did something else get covered up and then members of the Kehat family carry them out? The answer to that is in the beginning of last chapter.
“But Nadab and Abihu died by the will of Hashem for bringing a foreign fire” (Numbers 3:4).
וַיָּמָתוּ נָדָב וַאֲבִיהוּא לִפְנֵי י־הוָה בְּהַקְרִבָם אֵשׁ זָרָה לִפְנֵי י־הוָה (with “Hashem” read in place of the Name).
After Nadab and Abihu died, Moshe asked Mishael and Elzaphan his Kehati cousins to take the bodies out.
“They came forward and carried them out of the camp covered in their tunics, as Moses had ordered” (Leviticus 10:5).
וַיִּקְרְבוּ וַיִּשָּׂאֻם בְּכֻתֳּנֹתָם אֶל־מִחוּץ לַמַּחֲנֶה כַּאֲשֶׁר דִּבֶּר מֹשֶׁה.
This act of chesed done by the Kehati relatives of Aaron is later repaid by Hashem instructing the Kohanim to cover up all the sacred vessels for the Kehati family to carry out of the camp.