Irenaeus, Adversus omnes Haerses 3.9. In the fifth century, Leo the Great repeats this interpretation in Sermon 33, 34, 36 where he speaks of the One Person with a “three-fold function”: God, mortal human, and king. Compare Fulgentius of Ruspe (a North African writer, c. 467–533), Letter to Ferrandus 20.