There's one more reason to be excited to see BlacKkKlansman when it opens in theaters this week. Not only will we watch what's considered one of Spike Lee's finest films, but we'll also get to hear a rare recording of Prince singing "Mary Don't You Weep." Prince's version of the gospel song will be on the upcoming posthumous album from Warner Bros. and Prince's estate, Piano & a Microphone 1983. But Lee managed to get it early as the song that plays over BlacKkKlansman's closing credits. "I knew I needed an end-credits song," Lee told Rolling Stone. "I've become very close with (Prince estate entertainment adviser and former Spotify exec) Troy Carter. So I invited Troy to a private screening. And after, he said, 'Spike, I got the song.'" Carter, who had led Spotify's sponsorship of Lee's 2017 celebration of Prince, allowed Lee to use the cassette recording Prince made in the mid-1980s. Lee believes Prince had a hand in gifting the song. "Prince wanted me to have that song, I don't care what nobody says," he said. "My brother Prince wanted me to have that song. For this film. There's no other explanation to me. This cassette is in the back of the vaults. In Paisley Park. And all of a sudden, out of nowhere, it's discovered? Nah-ah. That ain't an accident!" Lee said the song was important for the final scene of the film, which includes the act of domestic terrorism in Charlottesville, Virginia, where Heather Heyer was killed. "I first needed to ask Ms. Susan Bro, the mother of Heather Heyer, for permission," he said. "Ths is someone whose daughter has been murdered in an American act of terrorism--homegrown, apple-pie, hot-dog, baseball, cotton-candy Americana. Mrs. Bro no longer has a daughter because an American terrorist drove that car down that crowded street. And even people who know that thing is coming, when they see it, it's like, very quiet. People sit there and listen to Prince singing a Negro spiritual, 'Mary Don't You Weep.'" BlacKkKlansman, based on the real story of a black detective infiltrating the KKK in the 1970s, stars John David Washington, Adam Driver, Laura Harrier, Corey Hawkins, Ato-Blankson-Wood, Damaris Lewis and Topher Grace. The film comes to theaters August 10. Piano & a Microphone 1983 will be released September 21.