I'm only finding the quote, no source. But here's something we can be sure he said:
> The complete syntax of LISP can be learned in an hour or so; the interpreter is compact and not exceedingly complicated, and students often can answer questions about the system by reading the interpreter program itself.
> The complete syntax of LISP can be learned in an hour or so; the interpreter is compact and not exceedingly complicated, and students often can answer questions about the system by reading the interpreter program itself.
https://web.media.mit.edu/~minsky/papers/TuringLecture/Turin...