This post is part of an ongoing series on Forgiveness in the Gospel of Matthew.
Peter’s question (a pattern in Matthew) and the parable which follows serve as a gemara, a safeguard against possible absolutist interpretations of the teaching on excommunication (vv.15-20) which precedes it. This brief dialogue introduces the topic of forgiveness, with the future verb ἀφήσω here connoting an imperative sense–how many times “must I forgive”? In contrast to Rabbinic limitations of forgiveness to four times, Peter recognizes Jesus’ greater righteousness and asks Jesus the equivalent of “Is perfect forgiveness expected of me?”
Jesus could have provided a simple “yes” to Peter’s question about the fullness of forgiveness, but he goes even further with the demands of forgiveness. Whether ἑβδομηκοντάκις ἑπτά means 490 or 77, “the point is that there can be no limits to the willingness to forgive.” Jesus’ unexpected answer provides a proverbial tone, leading quite naturally into the parable itself, which speaks of the extravagance of forgiveness in its first part.
 Davies and Allison, 791. Thompson 204-5.
 Luz, 465. Lambrecht, 54-56.
 Senior, 404. Cx. Amos 2.4, 6; Job 33.29.
 Luz, 465.
 Harrington, 269. See also Luz, 465, who writes that, “The most perfect, boundlessly infinite, countlessly repeated forgiveness is demanded of Peter.” Interestingly, Augustine recounts the 77 generations in Luke’s genealogy as the numerical indicator of why Christians are told to forgive 77 times. See Augustine, Sermon 83.5. Manlio Simonetti (ed.), Matthew 14-28: Ancient Christian Commentary on Scripture (Downers Grove, IL: InterVarsity Press, 2002), 83.
 Hagner, 537. Thompson, 207.