“These [eleh] were the sons of Levi by their names…” (Numbers 3:17) – Rabbi Abbahu said: Every place that eleh is stated, it rejects what preceded it; ve’eleh adds to what preceded it. Here, where it is stated: “These [eleh] were the sons of Levi by their names,” what does it reject? It rejects the firstborn of Israel, who worshipped the calf. “And these are the names of the sons of Gershon [by their families]” (Numbers 3:18) – see how beloved the Levites are, as the Holy One blessed be He engaged Himself in all their families to count their names, what He did not do regarding Israel.
That is what is written: “And these are the names of the sons of Gershon by their families: Livni and Shimi”; and likewise, “the sons of Kehat: Amram and Yitzhar, Ḥevron and Uziel” (Numbers 3:19); and likewise, “the sons of Merari by their families: Maḥli and Mushi” (Numbers 3:20). Our Rabbis said: These are the eight priestly watches25Each week a different shift worked in the Temple. that Moses instituted at the directive of the Holy One blessed be He, until David stood and rendered them twenty-four for the priesthood and the Levites.26Tosefta, Taanit 3:2.