In the early 80’s, sampling became both big and controversial. What was the first well-known song to sample another well-known song? I remember the 1982 song, “Planet Rock”, by Afrika Bambaataa & Soul Sonic Force using a chunk of Kraftwerk’s “Trans Europe Express” as a back beat.
Any earlier?
Google is indeed your friend. 
(“music sampling history” Google)
As beagledave’s link mentioned, the Sugar Hill Gang scratched recordings of a house band playing the songs. If you are refering to recorded music, I believe the Residents were doing a crude form of sampling in the 70’s, although the samples were pretty much unrecognizeable. If you are including live music, Grandmaster Flash was sampling in the 70’s, although he didn’t record until later. I am pretty sure John Cage experimented with music playback even earlier.
Revolution Number 9 used as its main riff a test sound of a man saying Number 9, over and over. This was a pre-recorded sound system test tape. On The Beatles “White Album”. It had not previously been a hit.
Various pre-recorded sound effects had been used for years over and over again for various reasons.