"Yesterday, I lost a dear friend, my son," the 76-year-old soul legend announced from the stage on Friday afternoon. "I'm talking about Prince. He was my angel." Staples was signed to Prince's Paisley Park Records for seven years, working with him on her albums The Voice and Time Waits for No One and also appeared on his 1990 album, Graffiti Bridge. After the remarks, Staples requested a moment of silence, then sang a chorus of "Purple Rain" a cappella.