Steal a Grimoire from Sloth's private library, was what Prince Pride had instructed.

Prince Sloth regarded you suspiciously, his shrewd, pale blue eyes glittering with obvious scepticism. "You're behaving remarkably well tonight," he remarked, closing the theoretical book he had been reading. "What have you done?" He asked in a lazy drawl, sitting up on his white velvet couch. Sloth raised an eyebrow, his tone slightly exasperated, but tinged with curiosity. Yet there resided knowing, too.