In chapter 35 in Don Quijote, Cervantes used a scene from "The golden ass" (unfortunate translation) from Apuleius. The rare version Cervantes did read in catholic Italy was a censored version. As he later read the original version in the king of Algiers's library, he thought his copying would never be spotted. By the way, what was the manchego slave doing in King of Algiers's library?
(9) (PDF) Miguel de Cervantes, slave, and his master Hassan Pacha Veneziano (researchgate.net)