חסידות אויף תהילים 32:7

This is the meaning of [the verse],³Psalms 32:7 “You conceal – Atah Seter (אתה סתר).” [The word Seter – Conceal (סתר)] is a backwards spelling of [the acronym] Rosh – Beginning (ראש), Toch – Middle (תוך), and Sof – End (סוף),⁴See Emek HaMelech, Shaar 12, Ch. 4. because the main restriction and concealment [of the Light] is in the externality of the vessels.