This was Marvin Gaye’s follow-up single to his No. 1 smash “Heard It Through the Grapevine,” and like that song it was written by Norman Whitfield and Barrett Strong — but not for that purpose. The tune was first released on a 1966 Temptation album, but was never released as a single. Whitfield retooled it for Gaye, and helped by the coattails of “Grapevine” it reached No. 4 on the Hot 100 and No. 5 in the UK. It was also the top-selling R&B single of 1969.
https://www.youtube.com/watch?v=z76RDhkB-6c
Here’s the original, which sounds softer and slower than Gaye’s version, though like the original it was produced by Whitfield himself. I take it as a demonstration of how much tougher the Motown sound got between 1966 and 1969.