Upcoming Netflix documentary Blood Brothers: Malcolm X & Muhammad Alidetails the three-year-long friendship between the civil rights and Nation of Islam leader and legendary boxer.

In the trailer, civil rights activist Reverend Al Sharpton praises the icons by declaring: “They define a whole generation to be themselves and be bold.”

Produced by Kenya Barris, the documentary will include interviews from relatives such as Ali’s younger brother Rahman Ali and Malcolm X’s daughter Ilyasah Shabazz. In another pivotal moment, Shabazz describes Malcolm X and Ali’s connection saying, “For my father to take his wife and his babies, and go to [Ali’s] home meant that my father trusted him 100 percent.”

When asked if he recalls his brother having any regrets, Rahman Ali tearfully responds, “That’s a hell of a question.”

Malcolm X and Ali bonded over the shared struggles of being Black leaders in America. Blood Brothers also chronicles the strained parts of their relationship and their disagreement over the leadership of the Nation of Islam. The documentary will show newly released clips that help provide a timeline for their friendship and fallout.

The film features images of Malcolm X and Ali together with their families and footage of them giving passionate quotes and speeches. The movie was inspired by a book of the same name written by Randy Roberts and Johnny Smith. Philosopher and political activist Cornel West also provides commentary.

Blood Brothers will be available to stream via Netflix on Sept. 9.