Hume, David (1748/1993), An Enquiry Concerning Human Understanding. Ed. by E. Steinberg. Indianapolis: Hackett. Sections IV-V.I. pdf

Further Reading:

Hume, David (1739/1896), A Treatise of Human Nature. Ed. by L.A. Selby-Bigge. Oxford: Clarendon Press. Book I, Part III, Sections 6 and 12. pdf