Stevie Wonder's "Superstition" was originally meant for which musician?

Stevie Wonder's "Superstition" hit number one in 1973 with a clavinet riff that made every rock station suddenly take notice. The funky groove was Wonder's most upbeat yet and proved he could cross over into any genre he wanted, but the song was supposed to be someone else's big moment. Who did Stevie Wonder originally write "Superstition" for?