Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Councils of Ancyra, Gangra, Neocæsarea, Antioch and Laodicea, which Canons were Accepted and Received by the Ecumenical Synods.: Canon XX

Canon XX.

If the wife of anyone has committed adultery or if any man commit adultery it seems fit that he shall be restored to full communion after seven years passed in the prescribed degrees [of penance].

Notes.

Ancient Epitome of Canon XX.

An adulteress and an adulterer are to be cut off for seven years.

Hefele.

The simplest explanation of this canon is “that the man or woman who has violated the marriage bond shall undergo a seven years’ penance” but many reject this explanation, because the text says αὐτὸν τύχειν and consequently can refer only to the husband.  Fleury and Routh think the canon speaks, as does the seventieth of Elvira, of a woman who has broken the marriage tie with the knowledge and consent of her husband.  The husband would therefore in this case be punished for this permission, just as if he had himself committed adultery.  Van Espen has given another explanation:  “That he who marries a woman already divorced for adultery is as criminal as if he had himself committed adultery.”  But this explanation appears to us more forced than that already given; and we think that the Greek commentators Balsamon and Zonaras were right in giving the explanation we have offered first as the most natural.  They think that the Synod punished every adulterer, whether man or woman, by a seven years’ penance.  There is no reason for making a mistake because only the word αὐτὸν occurs in the passage in which the penalty is fixed; for αὐτὸν here means the guilty party, and applies equally to the woman and the man:  besides, in the preceding canon the masculine ὅσοι ἐπαγγελλόμενοι includes young men and young women also.  It is probable that the Trullan Synod of 692, in forming its eighty-seventh canon, had in view the twentieth of Ancyra.  The sixty-ninth canon of Elvira condemned to a lighter punishment—only five years of penance—him who had been only once guilty of adultery.