Matthew 17:3

Irenaeus Against Heresies Book IV

And for this reason did He [the Lord] confer with him face to face on the top of a mountain, Elias being also present, as the Gospel relates,[294]

Tertullian A Treatise on the Soul

Now, not even to His apostles was His nature ever a matter of deception. He was truly both seen and heard upon the mount;[128]

Tertullian Against Praxeas

Since, therefore, He reserves to some future time His presence and speech face to face with Moses-a promise which was afterwards fulfilled in the retirement of the mount (of transfiguration), when as we read in the Gospel," Moses appeared talking with Jesus"[162]

Origen Commentary on Matthew Book XII

But when the Son of God in His transfiguration is so understood and beheld, that His face is a sun, and His garments white as the light, straightway there will appear to him who beholds Jesus in such form Moses,-the law-and Elijah,-in the way of synecdoche, not one prophet only, but all the prophets-holding converse with Jesus; for such is the force of the words "talking with Him; "[233]

Origen Commentary on Matthew Book XII

but, according to Luke, "Moses and Elijah appeared in glory," down to the words, "in Jerusalem."[234]