"Chopin never played his own pieces the same way twice."

I was looking for some record that Chopin supported the idea of never playing the same piece twice.  Perhaps there is a source other than Vladimir Horowitz's obituary. Fascinating!

Excerpt from
 

November 6, 1989

OBITUARY: Vladimir Horowitz, Titan of the Piano, Dies

By BERNARD HOLLAND

...
Mr. Horowitz was not overly worried by accusations of textual infidelity. "When I sit at the keyboard," he said, "I never know how I will play something [missing text]. The head, the intellect, is only the controlling factor of music making. It is not a guide. The guide is your feelings. Chopin never played his own pieces the same way twice."
At another time Mr. Horowitz said: "I am a 19th-century Romantic. I am the last. I take terrible risks. Because my playing is very clear, when I make a mistake, you hear it. But the score is not a bible, and I am never afraid to dare. The music is behind those dots. You search for it, and that is what I mean by the grand manner. I play, so to speak, from the other side of the score, looking back."