לְ֠אֵלֶּה מַחְלְק֨וֹת הַשֹּֽׁעֲרִ֜ים לְרָאשֵׁ֧י הַגְּבָרִ֛ים מִשְׁמָר֖וֹת לְעֻמַּ֣ת אֲחֵיהֶ֑ם לְשָׁרֵ֖ת בְּבֵ֥ית יְהוָֽה׃
These courses of the doorkeepers, even the chief men, had wards over against their brethren, to minister in the house of the LORD.
Read midrashic interpretation of I Chronicles 26:12: and classical rabbinic exegesis.