Ante-Nicene Fathers, Vol IX:
Origen's Commentary on the Gospel of Matthew.: Chapter V

5.  The Limit of Forgiveness.

“Then came Peter and said unto Him, Lord, how often shall my brother sin against me and I forgive him?” 6071   The conception that these things were said in a simple sense by Peter, as if he were inquiring whether he was to forgive his brother when he sinned against him seven times, but no longer if he sinned an eighth time, and by the Saviour, as if He thought that one should sit still and reckon up the sins of his neighbours against him in order that he might forgive seventy times and seven, but that from the seventy-eighth he should not forgive the man who wronged him, seems to me altogether silly and unworthy alike of the progress which Peter had made in the company of Jesus and of the divine magnanimity of Jesus.  Perhaps, then, these things also border on an obscurity akin to the words, “Hear My voice, ye p. 497 wives of Lamech,” 6072 etc.  If any one has already become a friend of Jesus so as to be taught by His spirit which illumines the reason of him who has advanced so far according to his desert, he might know the true meaning, therefore, in regard to these things, and such as Jesus Himself would have clearly expounded it; but we who fall short of the greatness of the friendship of Jesus must be content if we can babble a little about the passage.  The number six, then, appears to be working and toilsome, but the number seven to contain the idea of repose.  And consider if you can say that he, who loves the world and works the things of the world, and does those things which are material, sins six times, and that the number seven is the end of sin in his case, so that Peter with some such thought in his mind wished to pardon seven sins of those which his brother had committed against him.  But since as units the tens and the hundreds have a certain common measure of proportion to the number which is in units, and Jesus knew that the number might be exceeded, on this account, I think, that He added to the number seven also the seventy, 6073 and said that there ought to be forgiveness to brethren here, and to them who have sinned in respect to things here.  But if any one going beyond the things about the world and this age were to commit sin, even if it were trifling, he could not longer reasonably have forgiveness of sins; for forgiveness extends to the things here, and in relation to the sins committed here, whether the forgiveness comes late or soon; but there is no forgiveness, not even to a brother, who has sinned beyond the seven and seventy times.  But you might say that he who has sinned in such wise, whether as against Peter his brother, or as against Peter, against whom the gates of Hades do not prevail, is by sins of this kind in the smaller number of the sin, but according to sins still worse is in the number which has no forgiveness of sins.

Footnotes

Matt. xviii. 21.

Gen. iv. 23.

Matt. xviii. 22.