Whether it be 77 times or 490 times, the point is that there can be no limits to the willingness to forgive. The numbers allude to Gen. 4:24 "If Cain is avenged sevenfold, truly Lamech seventy-sevenfold." Jesus' reply to Peter reverses the Lamech principle of measureless blood vengeance. In fact under Lamech there was no limit to hatred and revenge. Under Moses it was limited to "an eye for an eye, tooth for tooth, a life for a life." Now under Jesus, there is no limit to love, forgiveness and mercy. However our forgiveness of our brother/sister is the condition of God's pardon for us. Only a forgiving spirit can receive forgiveness. Jesus illustrated this for His disciples through the parable of the Unforgiving/Unmerciful servant - who had received extravagant mercy from the king but responded to another with extravagant mercilessness.
While the first part of the parable focuses upon grace and mercy, the second part stresses the aspect of judgement. God's grace demands responsibility. It is freely given, nevertheless, it requires an appropriate response. The parable also dramatizes what is prayed in the Lord's Prayer: "forgive us our debts as we forgive our debtors" (Mt. 6:12).
Our debt to the Heavenly Father is immeasurable in comparison with our neighbour's debt to us. Therefore it is only if we are willing to forgive others that God forgives us. Besides, forgiveness must be "from the heart." It must be profound and absolute.
Lord, help me to live in the awareness of the Father's love and forgiveness already received.