This brief excerpt is from The Mayor of MacDougal Street, the memoirs of Dave Van Ronk (one of my heroes) page 75:
Years later, I was talking with him [Oscar Brand] and expressed my disgust that that he, or maybe someone else, had put on a show with Burl Ives, who had outraged us all by naming a string of names in front of HUAC. Oscar just quietly said, “Dave, we on the left do not blacklist.” Put me right in my place.
Do you mean Oscar Brand? Of “Four Letter Words” fame?
Yes. Corrected now. Thanks.
I have high but fragile hopes of the Coen Brothers biopic coming out
Yeah, exactly. Me too.
It was Zero Mostel who said that.