Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Synods of Sardica, Carthage, Constantinople, and Carthage Under St. Cyprian, Which Canons Were Received by the Council in Trullo and Ratified by II. Nice.: Canon CXI

Canon CXI.  (Greek cxiij.)

That the grace of God not only gives remission of sins, but also affords aid that we sin no more.

Likewise it seemed good, that whoever should say that the grace of God, by which a man is justified through Jesus Christ our Lord, avails only for the remission of past sins, and not for assistance against committing sins in the future, let him be anathema.

Ancient Epitome of Canon CXI.

Whoever is of opinion that the grace of God only gives remission of those sins we have already committed, and does not afford aid against sin in the future, is to be twice execrated.