Council of Ephesus
Likewise, if any should in any way attempt to set aside the orders in each case made by the holy Synod at Ephesus, the holy Synod decrees that, if they be bishops or clergymen, they shall absolutely forfeit their office; and, if laymen, that they shall be excommunicated.
Source details
A.D. 431 · Canon 6 (431)
Checked word-for-word against Nicene and Post-Nicene Fathers, Series 2, Vol. 14 · 2026-07-26