Canon 78

1Abṭelis, 88. Slaves shall not be ordained, nor numbered among the priesthood, except by the permission of their masters. For in this way, they become free and are placed among them. But if a slave is one who desires the priesthood, as Absyrtus or a similar name and his masters freed him and elevated him and brought him out from among them, and he is one who desires this, let him be ordained a priest.