Nachman of Breslov,
Likutei Moharan — 6
“ Even if, God forbid, he falls to wherever he falls - even into the deepest Hell - he must still never give himself over to despair, but constantly seek and search for God. No matter where he is, he must strengthen himself with all means available. For God is to be found even in the deepest Hell, and there too it is possible to attach oneself to Him. This corresponds to "and if I make my bed in Hell, here You are," the expertise of returning. For it is impossible to walk the pathways of repentance unless one possesses both these types of expertise. ”
