Numbers 3:20

And the sons, of Merari, by their families
The third son of Levi; Mahli and Mushi;
the same as in ( Exodus 6:19 ) ; from whom were denominated the families of the Mahlites and Mushites, who, as the preceding families, were numbered at this time: these [are] the families of the Levites, according to the house of their
fathers;
in all eight families.