Ray Charles Ft. In A Special Kenny Rogers (1979)

Photo taken during this show.

Ray Charles with Kenny Rogers,
Dottie West and The Oak Ridge Boys.

In early 1979 Kenny Rogers toured in the U.S. One of the tunes on his setlist was Oh Lady Luck. This set was one of the elements in a variety TV show titled A Special Kenny Rogers, where Kenny "returned to his home town of Crockett (TX)", directed by Rocco Urbisci or Stan Harros, and aired on April 12, 1979 by CBS.  The show, directed by Stan Harris, had been taped in February. Ray's segments were recorded on stage at the Opryland Auditorium in Nashville (see comment to this article); other parts were produced at the Houston Livestock and Rodeo Show (source here).
The guest stars - Ray, Lightnin' Hopkins (with an impromptu appearance), Dottie West and the Oakridge Boys - helped Kenny to "display the sights and sounds of East Texas which left their imprint on young Rogers".

Their duet on Oh Lady Luck wasn't great, but it certainly looked and sounded spontaneous. The song was written by Kenny Rogers and one of his band members, Steve Glassmeyer (cf. comments).
After this, Ray solo'ed with a great version of It Ain't Easy Being Green (using an orchestra tape).