Allah's Mercy Prevails Over His Wrath

On the authority of Abu Hurayrah (may Allah be pleased with him), who said that the Messenger of Allah (peace and blessings of Allah be upon him) said:

"When Allah decreed the Creation He pledged Himself by writing in His book which is laid down with Him: 'My mercy prevails over my wrath.'"

Hadith Qudsi [Muslim (also by al-Bukhari, an-Nasa'i and Ibn Majah)]

Narated By Safwan bin Muhriz : A man asked Ibn 'Umar, "What did you hear Allah's Apostle saying regarding
An-Najwa (secret talk between Allah and His believing worshipper on the Day of Judgment)?" He said, "(The
Prophet said), "One of you will come close to his Lord till He will shelter him in His screen and say: Did you commit
such-and-such sin? He will say, 'Yes.' Then Allah will say: Did you commit such and such sin? He will say, 'Yes.'
So Allah will make him confess (all his sins) and He will say, 'I screened them (your sins) for you in the world, and
today I forgive them for you.'"

Volumn 008, Book 073, Hadith Number 096

The Best Manner of Seeking Forgiveness

Syed-ul-Istighfaar
اللهم أنت ربي لا إله إلا أنت ، خلقتني وأنا عبدك ، وأنا على عهدك ووعدك ما استطعت ، أعوذ بك من شر ما صنعت ، أبوء لك بنعمتك علي وأبوء لك بذنبي فاغفر لي ، فإنه لا يغفر الذنوب إلا أنت

"O Allah! You are my Rabb. There is no true god except You. You have created me, and I am Your slave, and I hold to Your Covenant as far as I can. I seek refuge in You from the evil of what I have done. I acknowledge the favors that You have bestowed upon me, and I confess my sins. Pardon me, for none but You has the power to pardon."

Hadith:"He who supplicates in these terms during the day with firm belief in it and dies on the same day (before the evening), he will be one of the dwellers of Jannah; and if anyone supplicates in these terms during the night with firm belief in it and dies before the morning, he will be one of the dwellers of Jannah" (Al-Bukhari)

"And seek the forgiveness of Allah. Certainly, Allah is Ever Oft-Forgiving, Most Merciful.'' (4:106)