Second Council of Constantinople, Capitulum III

If anyone shall say that the wonder-working Word of God is one [Person] and the Christ that suffered another; or shall say that God the Word was with the woman-born Christ, or was in him as one person in another, but that he was not one and the same our Lord Jesus Christ, the Word of God, incarnate and made man, and that his miracles and the sufferings which of his own will he endured in the flesh were not of the same [Person]:  let him be anathema.

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