I just read that
I once saw him on TV, and he was introducing the next song, “Ain’t no sunshine when she’s gone” and told the story, that once he had accidentally introduced it as “Ain’t no sunshine til she’s gone.” and said “Well, must have thought about my second wife!”.
Here’s an older video of the song “Don’t let the sun go down on me” on YouTube. Again, I only link to YouTube for sakes of page loading time!
And here you can hear, not so much see, what he taught his students