On the PBS show Finding Your Roots Professor Henry Louis Gates Jr. uses genealogical research and genetics testing to reveal the ancestry of celebrities.

Nas was one of the guests last night on the show's season premiere, and Gates revealed to the Queensbridge rapper his great, great grandmother Pocahontas' bill sales for $830 as well as a photo of the slave owner who had bought her at age 15.

Nas was quite moved by what he saw. "A receipt for a human being," he said. "This is painful, now. To see that—that hurts."

Gates also showed Nas a photo of the home Pocahontas and his great, great grandfather were forced to work in until 1865, when they were freed by the end of the Civil War. It burned down in 1963, but Nas expressed interested in buying the land as a tribute to his ancestors. Check out a powerful clip from the segment.