When Ozzy Osbourne was fired from Black Sabbath in 1979, it marked the end of the original lineup’s classic era.

During a recent appearance on the Bob Lefsetz podcast, bassist Geezer Butler detailed the difficult decision to dismiss the Prince of Darkness.

“It was heartbreaking because we’d all grown up together. We fought against the odds together,” the bassist explained. “We performed miracles, making the band successful. And it was heartbreaking. It’s like cutting your arm off.”

Despite agonizing over the decision, Butler still believes it was the right move for all involved.

READ MORE: The Day Black Sabbath Fired Ozzy Osbourne

“He definitely needed a change of lifestyle at the time,” the rocker noted, pointing to Osbourne’s increasingly dangerous substance abuse habits. “We were all doing drugs and boozing and stuff like that, but we could still function. Whereas Ozzy, he wasn’t functioning anymore. And we got this house in Bel Air to write an album. Ozzy just wasn’t interested in the music that we were doing.”

According to Butler, the initial suggestion to fire Ozzy came from Black Sabbath’s guitarist, Tony Iommi.

“Eventually Tony says, ‘Ozzy’s got to go. He’s just not interested. The band’s not going to go anywhere if we keep on like this.’ And he says, ‘Actually I was a party the other night and I got talking to this guy called Ronnie James Dio, and he’s got an absolutely brilliant voice, and I think we should give him a go.’”

“So Tony came to the decision to get rid of Ozzy,” Butler continued. “We we hated doing it, but it had to happen for our sake and his sake. And it all worked out great in the end. And Ronnie James Dio came along… He sang to some of the stuff that we’d written and he was brilliant, absolutely just exactly what it needed. And that was the end of the Ozzy era.”

Getting Fired From Black Sabbath Hit Ozzy Osbourne ‘Like a Ton of Bricks’

As you’d expect, Osbourne was stunned when the band told him he was fired.

“He couldn’t believe it. I mean, it’s like a ton of bricks coming down on him,” Butler recalled, noting that Ozzy was suddenly alone. “I mean, we had each other, but Ozzy didn’t have anybody. And luckily that’s when Sharon came along and saved him.”

Following his dismissal, Osbourne rebounded with one of the greatest second acts in rock history. The singer branched out with a hugely successful solo career, which recently earned him a second induction into the Rock & Roll Hall of Fame.

READ MORE: Ozzy Osbourne Celebrated With All-Star Performance at Rock Hall

“It surprised me how fast he turned himself around,” Butler admitted, looking back. “And we were totally, really glad that he was successful and he turned his whole life around. It was great because he was successful and we were successful. We were, had one of the biggest selling albums ever of the Sabbath era, and he probably became bigger than Sabbath.”