אֵ֗לֶּה מַחְלְקוֹת֙ הַשֹּׁ֣עֲרִ֔ים לִבְנֵ֥י הַקָּרְחִ֖י וְלִבְנֵ֥י מְרָרִֽי׃
These were the courses of the doorkeepers; of the sons of the Korahites, and of the sons of Merari.
Read midrashic interpretation of I Chronicles 26:19: and classical rabbinic exegesis.