Peter was greatly struck with what Christ had just said about reconciliation of enemies; and he wanted to know what limits were to be imposed on his generosity, especially, it might be, if the offender made no reparation for his offence, and acknowledged not his wrong doing.
My brother. As Matthew 18:15, fellow disciple, neighbour. Till seven times? Peter doubtless thought that he was unusually liberal and generous in proposing such a measure of forgiveness. Seven is the number of completeness and plurality, and our Lord had used it in giving his sentence about forgiveness: "If he trespass against thee seven times in a day, and seven times in a day turn to thee again," etc.
(Luke 17:4). Some rabbis had fixed this limit from an erroneous interpretation of Amos 1:3; Amos 2:1. "For three transgressions, and for four," etc.; but the usual precept enjoined forgiveness of three offences only, drawing the line here, and having no pity for a fourth offence.
Ben-Sira bids a man admonish an offending neighbour twice, but is silent as to any further forgiveness (Ecclesiasticus 19:13-17). The Jews were very fond of defining and limiting moral obligations, as if they could be accurately prescribed by number.
Christ demolishes this attempt to define by law the measure of grace.