וְשָׁפְט֥וּ אֶת־הָעָ֖ם בְּכָל־עֵ֑ת אֶת־הַדָּבָ֤ר הַקָּשֶׁה֙ יְבִיא֣וּן אֶל־מֹשֶׁ֔ה וְכָל־הַדָּבָ֥ר הַקָּטֹ֖ן יִשְׁפּוּט֥וּ הֵֽם׃
And they judged the people at all seasons: the hard causes they brought unto Moses, but every small matter they judged themselves.
Read kabbalistic (mystical) interpretation of Exodus 18:26: and classical mystical sources.