Lucian, The Skythian or the Consul 2 (go here for the full text)
“During the great plague, the wife of Arhkiteles the Areopagite had a dream that a Skythian named Toxaris appeared to her and said that the Athenians could stop the plague if they sprinkled wine all over their sidewalks.
Once this was done with some frequency—for they Athenians did not neglect the advice once they heard it—either the wine dispelled some of the airborne sickness with its own smell or that hero Toxaris knew something special when he advised them, since he was actually a doctor.
For this reason the payment for his healing is offered even to this day in the form of a white horse sacrificed on his grave.”
Κατὰ τὸν λοιμὸν τὸν μέγαν ἔδοξεν ἡ Ἀρχιτέλους γυνή, Ἀρεοπαγίτου ἀνδρός, ἐπιστάντα οἱ τὸν Σκύθην κελεῦσαι εἰπεῖν Ἀθηναίοις ὅτι παύσονται τῷ λοιμῷ ἐχόμενοι, ἢν τοὺς στενωποὺς οἴνῳ πολλῷ ῥαίνωσι. τοῦτο συχνάκις γενόμενον—οὐ γὰρ ἠμέλησαν οἱ Ἀθηναῖοι ἀκούσαντες—ἔπαυσε μηκέτι λοιμώττειν αὐτούς, εἴτε ἀτμούς τινας πονηροὺς ὁ οἶνος σβέσας τῇ ὀδμῇ, εἴτε ἄλλο τι πλέον εἰδὼς ὁ ἥρως ὁ Τόξαρις, ἅτε ἰατρικὸς ὤν, συνεβούλευσεν. ὁ δ᾿ οὖν μισθὸς τῆς ἰάσεως ἔτι καὶ νῦν ἀποδίδοται αὐτῷ λευκὸς ἵππος καταθυόμενος ἐπὶ τῷ μνήματι