From a Wall Street Journal review by Priscilla M. Jensen headlined “‘Amazing Grace’ Review: A Hymn for the World’s Heart”:

‘Amazing grace,” intoned the eulogist, and repeated it. He began to sing: “how sweet the sound, that saved a wretch like me,” and the congregation, a bit startled, joined in, as the pianist scrambled to accompany them. The singer was President Barack Obama, who had been addressing mourners at a 2015 memorial service for the Rev. Clementa Pinckney and eight parishioners, African-Americans murdered by a white supremacist during Bible study at their Charleston, S.C., church.