Drake stole a jazz musician's lyrics and then lied on the album claiming that he got permission -- so claims the jazz musician's people.

The song in question is "Pound Cake/Paris Morton Music 2."

The song begins with a 35 second monologue from a 1982 song, "Jimmy Smith Rap" - recorded by jazz musician Jimmy Smith.

Jimmy's dead, but his Estate insists in the lawsuit NO permission was given nor did anyone ask for it. The Estate is going after Drake, Cash Money Records and a bunch of others ... seeking more than $300K.

Listen to both songs below:

Now listen to the original, "Jimmy Smith Rap"