Правило 3
The place in the diptych of the Bishop of Constantinople after the Bishop of Rome is established.
Let the Bishop of Constantinople have primacy of honor after the Bishop of Rome, because this city is the new Rome.
Greek original
Τὸν μέν τοι Κωνσταντινουπόλεως ἐπίσκοπον ἔχειν τὰ πρεσβεῖα τῆς τιμῆς μετὰ τὸν τῆς Ῥώμης ἐπίσκοπον, διὰ τὸ εἶναι αὐτὴν νέαν Ῥώμην.
Parallel canons
Трул.328