Council of Trent: Session VII, Reformation, Chapter II

CHAPTER II. The holders of several Cathedral churches are commanded to resign all but one, in a given manner and time.

No one, by whatsoever dignity, grade, or pre-eminence distinguished, shall presume, in contravention of the institutes of the sacred canons, to accept and to hold at the same time several Metropolitan, or Cathedral, churches, whether by title, or in commendam, or under any other name whatsoever; seeing that he is to be accounted exceedingly fortunate whose lot it is to rule one church well and fruitfully, and unto the salvation of the souls committed to him. But as to those who now hold several churches contrary to the tenor of the present decree, they shall be bound, retaining the one which they may prefer, to resign the rest, within six months if they are at the free disposal of the Apostolic See, in other cases within the year; otherwise those churches, the one last obtained only excepted, shall be from that moment deemed vacant.

Translation: J. Waterworth, The Canons and Decrees of the Council of Trent (1848), Hanover Historical Texts Project transcription (1995).