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 CXVI

Canon CXVI.  (Greek cxvii.)

That the Saints say with accuracy, “Forgive us our trespasses.”

Likewise also it seemed good, that whoever wished that these words of the Lord’s prayer, when we say, “Forgive us our trespasses” are said by the saints out of humility and not in truth let them be anathema.  For who would make a lying prayer, not to men but to God?  Who would say with his lips that he wished his sins forgiven him, but in his heart that he had no sins to be forgiven.

Notes.

Ancient Epitome of Canon CXVI.

(Lacking.)

This is Canon viij. of Carthage, a.d. 418.