Numbers 1:49 Kabbalah

אַ֣ךְ אֶת־מַטֵּ֤ה לֵוִי֙ לֹ֣א תִפְקֹ֔ד וְאֶת־רֹאשָׁ֖ם לֹ֣א תִשָּׂ֑א בְּת֖וֹךְ בְּנֵ֥י יִשְׂרָאֵֽל׃

’Howbeit the tribe of Levi thou shalt not number, neither shalt thou take the sum of them among the children of Israel;

Read kabbalistic (mystical) interpretation of Numbers 1:49: and classical mystical sources.