וְהֵֽבֵאתָ֤ אֶת־הַבַּדִּים֙ בַּטַּבָּעֹ֔ת עַ֖ל צַלְעֹ֣ת הָאָרֹ֑ן לָשֵׂ֥את אֶת־הָאָרֹ֖ן בָּהֶֽם׃
And thou shalt put the staves into the rings on the sides of the ark, wherewith to bear the ark.
Read kabbalistic (mystical) interpretation of Exodus 25:14: and classical mystical sources.