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 I

p. 63 The Canons of the Council of Ancyra.

(Found in Labbe and Cossart’s Concilia, and all Collections, in the Greek text together with several Latin versions of different dates.  Also in Justellus and Beveridge.  There will also be found annotations by Routh, and a reprint of the notes of Christopher Justellus and of Bp. Beveridge in Vol. IV. of the Reliquiæ Sacræ, ed. altera, 1846.)

Canon I.

With regard to those presbyters who have offered sacrifices and afterwards returned to the conflict, not with hypocrisy, but in sincerity, it has seemed good that they may retain the honour of their chair; provided they had not used management, arrangement, or persuasion, so as to appear to be subjected to the torture, when it was applied only in seeming and pretence.  Nevertheless it is not lawful for them to make the oblation, nor to preach, nor in short to perform any act of sacerdotal function.

Notes.

Ancient Epitome to Canons I. and II.

Presbyters and deacons who offered sacrifice and afterwards renewed the contest for the truth shall have only their seat and honour, but shall not perform any of the holy functions.

Zonaras.

Of those that yielded to the tyrants in the persecution, and offered sacrifice, some, after having been subjected to torture, being unable to withstand to the end its force and intensity, were conquered, and denied the faith; some, through effeminacy, before they experienced any suffering, gave way, and lest they should seem to sacrifice voluntarily they persuaded the executioners, either by bribes or entreaties, to manifest perhaps a greater degree of severity against them, and seemingly to apply the torture to them, in order that sacrificing under these circumstances they might seem to have denied Christ, conquered by force, and not through effeminacy.

Hefele.

It was quite justifiable, and in accordance with the ancient and severe discipline of the Church, when this Synod no longer allowed priests, even when sincerely penitent, to discharge priestly functions.  It was for this same reason that the two Spanish bishops, Martial and Basilides, were deposed, and that the judgment given against them was confirmed in 254 by an African synod held under St. Cyprian.

The reader will notice how clearly the functions of a presbyter are set forth in this canon as they were understood at that time, they were “to offer” (προσφέρειν), “to preach” (ὁμιλεῖν), and “to perform any act of sacerdotal function” (λειτουργεῖν τι τῶν ἱερατικῶν λειτουργιῶν).

This canon is in the Corpus Juris Canonici Decretum.  Pars I., Dist. l., c. xxxii.