Letter 39
3. Indeed Caelestinus, the presbyter of our brother and fellow bishop Serenus, who, in breaking out against the judgement of the pontiff and against the orders of the apostolic see, took it upon himself to administer holy communion to the aforementioned men, although he was not in a position to overlook the verdict of his own bishop, is expelled instantly from his ecclesiastical office, so that none of the ministers of the Church may seek to oppose the ordinances of the pontiff.
(trans. Neil – Allen 2014: 190)