וְאֵ֙לֶּה֙ שְׁמ֣וֹת הָֽאֲנָשִׁ֔ים אֲשֶׁ֥ר יַֽעַמְד֖וּ אִתְּכֶ֑ם לִרְאוּבֵ֕ן אֱלִיצ֖וּר בֶּן־שְׁדֵיאֽוּר׃
And these are the names of the men that shall stand with you: of Reuben, Elizur the son of Shedeur.
Read kabbalistic (mystical) interpretation of Numbers 1:5: and classical mystical sources.