Council of Chalcedon, Canon IV

Let those who truly and sincerely lead the monastic life be counted worthy of becoming honour; but, forasmuch as certain persons using the pretext of monasticism bring confusion both upon the churches and into political affairs by going about promiscuously in the cities, and at the same time seeking to establish Monasteries for themselves; it is decreed that no one anywhere build or found a monastery or oratory contrary to the will of the bishop of the city; and that the monks in every city and district shall be subject to the bishop, and embrace a quiet course of life, and give themselves only to fasting and prayer, remaining permanently in the places in which they were set apart; and they shall meddle neither in ecclesiastical nor in secular affairs, nor leave their own monasteries to take part in such; unless, indeed, they should at any time through urgent necessity be appointed thereto by the bishop of the city.  And no slave shall be received into any monastery to become a monk against the will of his master.  And if any one shall transgress this our judgment, we have decreed that he shall be excommunicated, that the name of God be not blasphemed.  But the bishop of the city must make the needful provision for the monasteries.

Translation: Henry R. Percival, The Seven Ecumenical Councils, NPNF II.14 (1900), via CCEL.