Acts 9:5

Τίς εἶ, Κύριε; the title is here used in reverent and awestruck response to the question of a speaker, in whose voice, accompanied as it was by the supernatural light, Saul recognised a divine utterance it is therefore more than a mere word of respect, as in Acts 16:30; Acts 25:26; it indicates, as St. Chrysostum noted, a purpose to follow the voice, whether it was that of an angel or of God Himself (Felten), “Jam parat se ad obediendum, qui prius insaniebat ad persequendum,” Augustine. Ἐγὼ … σὺ : both pronouns are emphatic, and contrasted: Ἰησοῦς, cf. Acts 20:8, and note. For rest of verse see critical notes.