High Tide or Low tide
Rastaman Chant
Walk The Proud Land
Duppy Conqueror
Shit, they are all pretty great. Any of the stuff with him Peter Tosh and Bunny Wailer is just unbeatable.
While we are on the subject, they re-released the album Talkin' Blues a couple of years ago, remastered with some bonus tracks. If you don't have it, buy it, it is unreal.
There are only two mantras. Yum and yuk. Mine's yum.