In the song “Ain’t No Sunshine”, Bill Withers continues to sing “I know, I know” repeatedly, over and over.
Others who recorded the song, with the seemingly endless repetition, include Michael Jackson, Paul McCartney, Prince, Sting, Isaac Hayes and Tom Jones.
However, “I know” was never a part of the lyrics.
Withers was a factory worker who was too busy to write all the lyrics to the melody he had written. When he got in the studio he threw in the words “I know” temporarily, as a filler until he had the lyrics. Graham Nash, Stephen Stills and Booker G., all experienced performers, were also in the studio. They told Withers that it sounded fine. Deferring to their expertise, Withers never did complete the lyrics and left in the rather bizarre phrase. The rest, as they say, is history.