Numbers 4:28

וְאֵת קַלְעֵי הֶֽחָצֵר וְאֶת־מָסַךְ פֶּתַח שַׁעַר הֶחָצֵר אֲשֶׁר עַל־הַמִּשְׁכָּן וְעַל־הַמִּזְבֵּחַ סָבִיב וְאֵת מֵֽיתְרֵיהֶם וְאֶֽת־כָּל־כְּלֵי עֲבֹדָתָם וְאֵת כָּל־אֲשֶׁר יֵעָשֶׂה לָהֶם וְעָבָֽדוּ

and the hangings of the court, and the screen for the door of the gate of the court, which is by the tabernacle and by the altar round about, and their cords, and all the instruments of their service, and whatsoever there may be to do with them, therein shall they serve.

עַל־פִּי אַהֲרֹן וּבָנָיו תִּהְיֶה כָּל־עֲבֹדַת בְּנֵי הַגֵּרְשֻׁנִּי לְכָל־מַשָּׂאָם וּלְכֹל עֲבֹדָתָם וּפְקַדְתֶּם עֲלֵהֶם בְּמִשְׁמֶרֶת אֵת כָּל־מַשָּׂאָֽם

At the commandment of Aaron and his sons shall be all the service of the sons of the Gershonites, in all their burden, and in all their service; and ye shall appoint unto them in charge all their burden.

בְּנֵי מְרָרִי לְמִשְׁפְּחֹתָם לְבֵית־אֲבֹתָם תִּפְקֹד אֹתָֽם

As for the sons of Merari, thou shalt number them by their families, by their fathers’houses;

מִבֶּן שְׁלֹשִׁים שָׁנָה וָמַעְלָה וְעַד בֶּן־חֲמִשִּׁים שָׁנָה תִּפְקְדֵם כָּל־הַבָּא לַצָּבָא לַעֲבֹד אֶת־עֲבֹדַת אֹהֶל מוֹעֵֽד

from thirty years old and upward even unto fifty years old shalt thou number them, every one that entereth upon the service, to do the work of the tent of meeting.