Ambrose of Milan
Catena Aurea · Lukasevangelium 17
Lk 17, Verses 3–4English original
Take heed to yourselves: If thy brother trespass against thee, rebuke him; and if he repent, forgive him. And if he trespass against thee seven times in a day, and seven times in a day turn again to thee, saying, I repent; thou shalt forgive him.
Or this number is used because God rested on the seventh day from His works. After the seventh day of the world everlasting rest is promised us, that as the evil works of that world shall then cease, so also may the sharpness of punishment be abated.