A Church still undivided

The Constantinopolitan patriarch Photius praises the respect for the Eastern tradition of Popes Leo IV and Benedict III

Fozio's translation by Lorenzo Bianchi

And this thing [that is reciting the Creed in Greek in its earliest version] was done not only during the pontificate of Leo IV; but also Benedict, mild and meek and famous for his ascetics practices, his successor to pontifical see, strove not to come second to him (if chronological reasons made him second) in protecting and giving stability to what had been fixed.
And since somebody after them, feigning respect with devilish and false words (in fact he did not dare openly challenge their excellent and godly decisions), decided, with the apparently well-argued reason that that symbol of the faith should not be diffused on the mouth of all, rooted out from the Churches and broke off that godly and useful work that I have recorded (and I have no intention of giving further notice to these sacrilegious acts by indicating the name of their authors), he will know, even already knows and pays, with severity and sorrowful, the punishments for his wily rashness. So let him (for he too remains silent, even if unwilling) be repulsed into the place of silence and there remain.
Leo however, voice of God, not only manifested this industrious concern, good and inspired by God, in doing what we said earlier, but also did other: since in the treasury of the princes of the apostles Peter and Paul, among those sacred remains, were preserved from the earliest times, when piety was still alive, two shields or tablets that with Greek letters and words displayed the several times recalled sacred exposition of our faith, he ordered that they be read in public before the Roman people and be exposed to the sight of all, and many of those who then saw and read these things, are still now among the living.

Photius, De Spiritus Sancti mystagogia (PG. 102, 378-379)