President Obama delivered a powerful rendition of "Amazing Grace" at the funeral of slain Rev. Clementa Pinckney, and called on the country to honor those killed in the South Carolina church massacre.

President Barack Obama flew to South Carolina to deliver ... made him want to write a book about the song. OBAMA: (Singing) Amazing Grace. WALVIN: Waited a second and then began to sing "Amazing ...

President Barack Obama flew to South Carolina to deliver the eulogy ... it was this moment that made him want to write a book about the song. OBAMA: (Singing) Amazing grace, how sweet the sound ...