Covers:

1972:

Joe Simon [possibly recorded first, but in any case released afterwards]

1973:

Buddy Miles

1973:

Pearls

1974:

Diana Ross & Marvin Gaye

1974:

Claude François [as Tu es tout pour moi]

1977:

Maxine Nightingale

1978:

Roberta Flack

1981:

Chosen Few [as You Are Everything To Me]

1988:

Judas Priest [produced by Stock-Aitken-Waterman, wisely not released for fear of hardcore Priest fans reaction; just one minute survived (on YouTube)]

1991:

Kim Carnes

1991:

Rod Stewart [on CD Vagabond Heart]

1995:

Melanie Williams & Joe Roberts

1995:

Regina Belle

2003:

Michael McDonald

2004:

Hall & Oates

2005:

Vanessa Williams