Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Councils of Ancyra, Gangra, Neocæsarea, Antioch and Laodicea, which Canons were Accepted and Received by the Ecumenical Synods.: Canon XXII

Canon XXII.

Let not a bishop go to a strange city, which is not subject to himself, nor into a district which does not belong to him, either to ordain any one, or to appoint presbyters or deacons to places within the jurisdiction of another bishop, unless with the consent of the proper bishop of the place.  And if any one shall presume to do any such thing, the ordination shall be void, and he himself shall be punished by the synod.

Notes.

Ancient Epitome of Canon XXII.

A bishop shall not go from city to city ordaining people, except by the will of the bishop of the city:  otherwise the ordination shall be without force, and he himself exposed to censure.

If we do not draw a rash conclusion, we should say that the interference of bishops in dioceses not their own, must have been very frequent in early days.  This one synod enacted two canons (number XIII. and this present canon) on the subject.  The same prohibition is found in canons XIV. and XXXV. of the Apostolic canons, in canon XV. of Nice, canon ij. of I. Constantinople and in many others.  On account of the similarity of this canon to canon xiii. some have supposed it to be spurious, the enactment of some other synod, and this was the opinion of Godefrides Hermantius (Vita S. Athanasii, Lib. IV., cap. xij.) as well as of Alexander Natalis (Hist. Sœc., IV., Dissert. xxv.).  Van Espen, however, is of opinion that the two canons do not cover exactly the same ground, for he says Canon XIII. requires letters both from the Metropolitan and from the other bishops of the province, while this canon XXII. requires only the consent of the diocesan.  He concludes that Canon XIII. refers to a diocese sede vacante, when the Metropolitan with the other bishops took care of the widowed church, but that Canon XXII. refers to a diocese with its own bishop, whose will is all that is needed for the performance of episcopal acts by another bishop.  And this distinction Schelestratius makes still more evident by his discussion of the matter in his scholion on Canon XIII.

Compare with this canon of the Apostolic Canons number XXXV. also number XIV.

This canon is found in the Corpus Juris Canonici, Gratian’s Decretum, Pars II., Causa IX., Quæst. II., can. vij., but in a form differing far from the Greek original, as the Roman Correctors point out; and even Gratian’s present text is not as he wrote it, but amended.