South African musician Johnny Clegg, passed away on Tuesday at his home in Johannesburg, following a four year battle with pancreatic cancer, Reuters reports. He was 66.

The artist was the founder of the bands Juluka and Savuka, two mixed-raced bands formed during the apartheid era. He was known as a vocal critic of the apartheid regime, writing the 1987 song "Asimbonanga" for a then incarcerated Nelson Mandela. The song became a rallying cry for South Africans fighting or freedom.

He performed the tribute with Mandela on stage in 1999, which you can watch below.