Archbishop Desmond Tutu died on Sunday in Cape Town, South Africa. He was 90.

A tireless human rights advocate, Tutu had been in ill health for years, according to CNN.

For six decades, Tutu was outspoken about ending apartheid – South Africa's policy of racial segregation. The policy ended in the early 90s.

In 1984, Tutu was awarded the Nobel Peace Prize for his work speaking out against apartheid.

Former President Barack Obama in 2009 awarded Tutu the Presidential Medal of Freedom for his human rights advocacy.

Tutu also advocated for greater LGBTQ rights, including calling on nations to decriminalize gay sex.

In several interviews, Tutu said that God had commanded him to speak out on LGBTQ rights.

“It isn't that it's questionable when you speak up for the right of people with different sexual orientation,” he told Religious News Service. “People took some part of us and used it to discriminate against us. In our case, it was our ethnicity; it's precisely the same thing for sexual orientation. People are killed because they're gay. I don't think, 'What do I want to do today? I want to speak up on gay rights.' No. It's God catching me by my neck. I wish I could keep quiet about the plight of the Palestinians. I can't! The God who was there and showed that we should become free is the God described in the Scriptures as the same yesterday, today and forever.”

In 2013, Tutu appeared in a video for the United Nation's Free & Equal campaign. He told viewers that he could not keep quiet about anti-LGBTQ discrimination.

“I oppose such injustice with the same passion that I opposed apartheid,” he said in the spot.