This is attributed to Anne Sexton, the late American confessional poet.
"Put your ear down close to your soul and listen hard."
I use it in my artwork often, too . . . it's much more than a "writing quote," in my opinion--for anyone seeking a muse, trying to find a voice, looking for the "right" way to express oneself, these are words to live by. [Or, as the English teacher in me would like to say, words by which to live.]
By the way, this is my favorite photo of Sexton . . . she was a glamorous woman, almost always photographed with a cigarette in her hand.