The present dissertation, based on an exegetical analysis of Nm 18,1-7, studies the functions and cultic services performed by the priests and Levites, particularly the Kohathites. Given that, over the past four decades, there has not been much work on the book of Numbers, in particular on Nm 18,1-7, it is believed that this research makes a modest contribution. An exegetical analysis of the text was the main objective, investigating the role of Aaron and his sons (priests) in the exercise of their functions in the Tent of Meeting, being assisted by the Levites, in order to preserve the holiness of the community of Israel thereby preventing the death of its members. Hence, it is clear that Nm 18,1-7 confirms the importance of the priestly current in the final writing of the book of Numbers. Despite of containing non-priestly materials, this book highlights and attests to the fundamental role of priests and Levites in favor of Israel. The historical-critical method was used as an indispensable tool to reach a deeper and better understanding of Nm 18,1-7. It is observed that the section has an introduction and seven subsections, which form a chiasm, corroborated by the syntactic and semantic elements that compose it. Aaron is the central character and direct recipient of YHWH s word. By classifying Nm 18,1-7 as a priestly torah, one attests to the sacredness of the worship and of the service of priests and Levites, whereby Israel can be preserved from conflict and mortal damage (cf. Nm 16–17).