What is the earliest commentary on John 20:28?

Thomas' statement at John 20:28 > "Thomas replied, “My Lord and my God!”" > Ἀπεκρίθη Θωμᾶς καὶ εἶπεν αὐτῷ “Ὁ Κύριός μου καὶ ὁ Θεός μου.” has been the subject of significantly different interpretations. Some, and now this seems the standard view, hold that Thomas is saying Jesus is both Thomas' Lord and God, where 'God' is understood in something like a Trinitarian sense. There are other interpretations , including calling Jesus a 'god', an exclamation of astonishment, or Thomas seeing the Father in Jesus because he now knows Jesus is the agent of the Father. What is the earliest known commentary on John 20:28? How does the commenter (or commenters if they are roughly contemporaneous) understand Thomas' statement?