וְעַתָּ֗ה קְח֤וּ לָכֶם֙ שְׁנֵ֣י עָשָׂ֣ר אִ֔ישׁ מִשִּׁבְטֵ֖י יִשְׂרָאֵ֑ל אִישׁ־אֶחָ֥ד אִישׁ־אֶחָ֖ד לַשָּֽׁבֶט׃
Now therefore take you twelve men out of the tribes of Israel, for every tribe a man.
Read kabbalistic (mystical) interpretation of Joshua 3:12: and classical mystical sources.