The Synod of Antioch in Encaeniis (341 AD)

No bishop shall presume to pass from one province to another, and ordain persons to the dignity of the ministry in the Church, not even should he have others with him, unless he should go at the written invitation of the metropolitan and bishops into whose country he goes. But if he should, without invitation, proceed irregularly to the ordination of any, or to the regulation of ecclesiastical affairs which do not concern him, the things done by him are null, and he himself shall suffer the due punishment of his irregularity and his unreasonable undertaking, by being forthwith deposed by the holy Synod.

Ancient Epitome of Canon XIII.

If without invitation a bishop shall go into another province, and shall ordain, and administer affairs, what he does shall be void and he himself shall be deposed.

Compare with this Apostolic Canon xxxv.; also canon xxii. of this same synod.

This canon is found in the Corpus Juris Canonici, Gratian’s Decretum, Pars II., Causa ix., Quæst. II., Can. vj. in the Versio Prisca. The Roman Correctors are not satisfied with it, however, nor with any version and give the Greek text, to which they add an accurate translation.