וְרָחֲצ֣וּ מִמֶּ֔נּוּ מֹשֶׁ֖ה וְאַהֲרֹ֣ן וּבָנָ֑יו אֶת־יְדֵיהֶ֖ם וְאֶת־רַגְלֵיהֶֽם׃
that Moses and Aaron and his sons might wash their hands and their feet thereat;
Read kabbalistic (mystical) interpretation of Exodus 40:31: and classical mystical sources.