Searching for a sample in a hiphop track, probably from a 70s soul hit

I really like the music in the track below, and I'm about 99 % sure it's sampled from another (probably very old) song.

Does somebody have any idea where the music has been sampled from?

02-Dj Quik And Kurupt-Cream N Ya Panties.wmv - YouTube

Thanks already. :)