Catholic interpreters of the Scriptures have long noted the typological connection between the “keys” passed on in Isaiah 22 and Jesus’ bestowal of the keys in Matthew 16:18. The “keys” connection seems obvious to many modern Protestant biblical interpreters as well (see here for many examples). Last week, when I was speaking at Franciscan University’s “Defending the Faith” conference, a young man asked me if the pairing appears anywhere in the Fathers or the ancient lectionaries. So far, the only incidence I’ve been able to track is in St. Ephrem of Syria (fourth century):
Therefore the former Steward and the last Treasurer handed on the keys of the priesthood and prophecy to him who had authority over the treasury of both of these. Because of this his Father gave him the Spirit without measure, because all the measures of the Spirit are under his hand. And our Lord, to show that he had received the keys from the former steward, said to Simon: To thee will I give the keys of the gates. But how could he give them to another unless he had received them from another? THe keys, therefore, which he received from Simeon the priest, he gave to ‘Simeon’ the Apostle, so that even if the Nation would not listen to the former Simeon, the Nations should listen to the other ‘Simeon.”
But since John also was a treasurer, of baptism, to him also came the Lord of stewardship, to receive from him the keys of the House of Absolution.
In his excellent book The Biblical Basis for the Papacy, John Salza provides a 27-page patristic catena on the papacy. In his section on “keys,” he cites Asterius, Pope Celestine, Optatus, Tertullian, Hippolytus, Aphrahat, Cyril of Jerusalem, Ephrem, Hilary, Gregory of Nazianzus, Basil, Ambrosiaster, Didymus, Epiphanius, Ambrose, Augustine, and Pope Felix. Some of his citations use one of those passages, and some use the other, but none use both.
If anyone knows other examples, please let me know.