Daniel Bukszpan, who wrote a biography about Ozzy Osbourne in 2023, couldn’t bring himself to watch the rocker’s farewell concert that took place less than three weeks before his death.

The Black Sabbath bassist shared details of Osbourne’s final performance, including how “frail” he had become, in an essay for the Sunday Times. Butler said the iconic rocker needed the assistance of three people while rehearsing and had to sit down while he sang.