Council of Ephesus
Council of Ephesus, Canon IV
Selected letters, decrees and canons, including Cyril’s anathemas with reception notes; not the full proceedings
Canon IV
If any of the clergy should fall away, and publicly or privately presume to maintain the doctrines of Nestorius or Celestius, it is declared just by the holy Synod that these also should be deposed.
Translation: Henry R. Percival, The Seven Ecumenical Councils, NPNF II.14 (1900), via CCEL.
Source: Council of Ephesus (CCEL)