Geezer Butler from Black Sabbath/Heaven And Hell in Classic Rock magazine March 2010:
Classic Rock: Finally, can you actually reveal the truth about the long standing rumours that Sabbath and Led Zeppelin jammed together in the studio, and that it was recorded?
Geezer Butler: It did happen, yes. When we did "Sabotage" in early 1975 at Morgan Studios in north-west London. The Zeppelin guys came down, and both bands did get together for a jam. I have no clue if it was recorded though. I suspect it was, but what happend to the tapes... who knows? They might even have been wiped. But in those days everything was recorded, which is why you ended up with things like "The Trogg Tapes". Do we have an equivalent of that? Yes, it was called the "Volume 4" album!
But we were on very good terms socially with Zeppelin, especially with John Bonham. We spent many night drinking with him and putting stuff up our noses. That's probably the thing which amazes me most: with all the things we got up to back then, how am I still alive?