The song is the recurring theme to the TV miniseries "East of Eden". It is a gorgeous piece of music.
I have never been a stickler for avoiding music simply beacause it had been used by another performer in the past, but the show that this music came from is so obscure that the music would probably never be "stumbled upon" by anyone. It is pretty much identified with David, so I would tend to stay away from it as an illusion piece.
If you would like to hear a very nice vocal version of the song, do a Google search for "Molly-Ann Leiken" and look for "An American Hymn".