Tony Iommi, Black Sabbath guitarist and co-founder, told UK broadcaster ITV that Osbourne was “frustrated” during the band’s farewell concert on July 5. The heavy metal icon died less than three weeks later, on July 22, at age 76.

On July 5, the Aquaman actor hosted the legendary rocker's final Black Sabbath concert in Osbourne's hometown of Birmingham, England. Four days before Osbourne's death at age 76 on Tuesday July 22, Momoa spoke with PEOPLE about the experience while doing press for his new Apple TV+ series Chief of War.

Osbourne died on Tuesday at 76, just weeks after he and Black Sabbath performed at their farewell Back to the Beginning concert earlier in July.