עַל־פִּ֨י יְהוָ֜ה פָּקַ֤ד אוֹתָם֙ בְּיַד־מֹשֶׁ֔ה אִ֥ישׁ אִ֛ישׁ עַל־עֲבֹדָת֖וֹ וְעַל־מַשָּׂא֑וֹ וּפְקֻדָ֕יו אֲשֶׁר־צִוָּ֥ה יְהוָ֖ה אֶת־מֹשֶֽׁה׃ (פ)
According to the commandment of the LORD they were appointed by the hand of Moses, every one to his service, and to his burden; they were also numbered, as the LORD commanded Moses.
Read kabbalistic (mystical) interpretation of Numbers 4:49: and classical mystical sources.