Komentarz do Liczb 4:3

לעשות מלאכה, to perform work, etc. The Torah describes the task of the Kehatites differently from that of the sons of Gershon and that of the sons of Merari where the Torah uses the term לעבוד עבודה. The Torah was anxious to make it plain that though the Kehatites entered the Tabernacle what they did there did not qualify as עבודה, as priestly service. On the contrary, the ark is reputed to have carried its carriers as we know from Bamidbar Rabbah 4. What the Kehatites did was simply מלאכה, ordinary work. Furthermore, because the Kehatites had to carry the Holy Ark on their shoulders, i.e. perform physical labour as part of their assigned tasks, the Torah used the appropriate word מלאכה to describe their function. The tasks to be performed by the clan of Gershon and Merari respectively did not entail physical work of any major kind.

V. 3. כל בא לצבא siehe zu Kap. 1, 3.