dark night of the soul
Concise Oxford English Dictionary © 2008 Oxford University Press:
dark night of the soul
▶noun a period of spiritual desolation suffered by a mystic in which all sense of consolation is removed.
– origin C19: used to translate Sp. Noche oscura, the title of a poem by the Spanish mystic St John of the Cross.
'dark night of the soul' also found in these Oxford entries:

