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 IX

p. 129 Canon IX.

The members of the Church are not allowed to meet in the cemeteries, nor attend the so-called martyries of any of the heretics, for prayer or service; but such as so do, if they be communicants, shall be excommunicated for a time; but if they repent and confess that they have sinned they shall be received.

Notes.

Ancient Epitome of Canon IX.

Whoso prayeth in the cemeteries and martyries of heretics is to be excommunicated.

Zonaras.

By the word “service” (θεραπείας) in this canon is to be understood the healing of sickness.  The canon wishes that the faithful should under no pretence betake themselves to the prayers of heretical pseudo-martyrs nor pay them honour in the hope of obtaining the healing of sickness or the cure of their various temptations.  And if any do so, they are to be cut off, that is for a time forbidden communion (and this refers to the faithful who are only laymen), but when they have done penance and made confession of their fault, the canon orders that they are to be received back again.

Balsamon.

As canon vi. forbids heretics to enter the house of God, so this canon forbids the faithful to go to the cemeteries of heretics, which are called by them “Martyries.”…For in the days of the persecution, certain of the heretics, calling themselves Christians, suffered even to death, and hence those who shared their opinions called them “martyrs.”

Van Espen.

As Catholics had their martyrs, so too had the heretics, and especially the Montanists or Phrygians, who greatly boasted of them.  Apollinaris writes of these as may be seen in Eusebius (H. E., Lib. v., cap. xvj.)

The places or cemeteries in which rested the bodies of those they boasted of as martyrs, they styled “Martyries” (martyria) as similar places among Catholics were wont to be called by the same name, from the bones of the martyrs that rested there.

From the Greek text, as also from Isidore’s version it is clear that this canon refers to all the faithful generally, and that “the members of the Church” (Lat. Ecclesiastici, the word Dionysius uses) must be taken in this wide signification.