Aliceson Kraus sings the song, Down to the River to Pray, the movie is Oh Brother where art thou

There is a song that I remember singing about 20yrs ago in church but I forgot some of the words. The words I remember are
(preach the gospel tell it like it is, tell the congregation you must be born again, don't sugar coat your messages with lies so full of sin, for God will just reward you when ...