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 XII

Bishops are to be appointed to the ecclesiastical government by the judgment of the metropolitans and neighbouring bishops, after having been long proved both in the foundation of their faith and in the conversation of an honest life. Whoever is most approved in faith and life and most learned, he is fit to be chosen bishop. The first part of this canon is in conformity with the provision in the IV. canon of Nice.