2 In this connection it should be borne in mind that the orientals need have no fear at all of being compelled to abandon their lawful rites and customs if unity of faith and government is restored; our predecessors have more than once made this absolutely clear. "Nor is there any reason for you to fear on that account that we or any of our successors will ever diminish your rights, the privileges of your patriarchs, or the established ritual of any one of your churches."
Source: Orientales Omnes Ecclesias (Vatican.va)