וּבְנֵ֧י מְרָרִ֛י לְמִשְׁפְּחֹתָ֖ם מַחְלִ֣י וּמוּשִׁ֑י אֵ֥לֶּה הֵ֛ם מִשְׁפְּחֹ֥ת הַלֵּוִ֖י לְבֵ֥ית אֲבֹתָֽם׃
And the sons of Merari by their families: Mahli and Mushi. These are the families of the Levites according to their fathers’houses.
Read kabbalistic (mystical) interpretation of Numbers 3:20: and classical mystical sources.