A Muslim knowing that Allah has forgiven them

Q 1: During Jumu`ah (Friday) Prayer, I heard the Khatib (preacher) say "The servant knows when Allah forgives him," is this right and how is this possible?

A: The Muslim repents to Allah and hopes for acceptance of his repentance and forgiveness of his sins, for Allah (Exalted be He) says, Say: "O ‘Ibâdî (My slaves) who have transgressed against themselves (by committing evil deeds and sins)! Despair not of the Mercy of Allâh: verily, Allâh forgives all sins. Truly He is Oft-Forgiving, Most Merciful. However, no Muslim should claim their being quite sure that Allah has forgiven them except with proof from the Qur'an and Sunnah. As for this Khatib's saying, it is baseless.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.