Hadith Qudsi 34:
On the authority of Anas (may Allah be pleased with him), who said: I heard the Messenger of Allah (PBUH) say: Allah the Almighty said:
"Oh son of Adam, so long as you call upon Me and ask of Me, I shall forgive you for what you have done, and I shall not mind. O son of Adam, were your sins to reach the clouds of the sky and were you then to ask forgiveness of Me, I would forgive you. O son of Adam, were you to come to Me with sins nearly as great as the earth and were you then to face Me, ascribing no partner to Me, I would bring you forgiveness nearly as great at it."
[It was related by at-Tirmidhi (also by Ahmad ibn Hanbal). Its chain of authorities is sound]
003. Release your grudges, the painful memories, and the hurt you ensued at the hands, words, and actions of others, by extending your hand to Him; in supplication.
The Prophet (PBUH) said, “Whoever established prayers on the night of Qadr out of sincere faith and hoping for a reward from Allah, then all his previous sins will be forgiven; and whoever fasts in the month of Ramadan out of sincere faith, and hoping for a reward from Allah, then all his previous sins will be forgiven.”
(Narrated By Abu Huraira. Sahih Bukhari: Volume 003, Book 031, Hadith Number 125.)