We forbid all the clergy who adhere to the Orthodox and Ecumenical Synod in any way to submit to the bishops who have already apostatized or shall hereafter apostatize.

CANON III OF THE THIRD AND HOLY ECUMENICAL COUNCIL
IF any of the city or country clergy have been inhibited by Nestorius or his followers from the exercise of the priesthood, on account of their orthodoxy, we have declared it just that these should be restored to their proper rank. And in general, we forbid all the clergy who adhere to the Orthodox and Ecumenical Synod in any way to submit to the bishops who have already apostatized or shall hereafter apostatize.