Allah, al Rahman

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.
-Muslim

O 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.
- At-Tirmidhi

Indeed, no one despairs of relief from Allah except the disbelieving people.
Surat Yusuf:87

He said: "My Lord! Verily, I have wronged myself, so forgive me."
Then He forgave him.
Verily, He is the Oft-Forgiving, the Most Merciful.
-Surat Al Qasas :16

-he was Moses and the Forgiver was Allah, Al Ghafur. The verse was concerning Moses' supplication to Allah concerning the Copt he had killed earlier. And remember Aadam (alayhi salam) - our father , our first Prophet. Did he not commit a great sin that resulted in him being placed on Earth from Paradise?

Never despair of Allah's Mercy, His Infinite Mercy. Think for a moment, if it wasn't for His Mercy what state would we all be in. Remember , we're human, insaan, which is derived from the arabic word nasiya - to forget. My, what copious excuses we have simply for being humans, momentary excuses, that is.

Point is, try not to forget Allah's Mercy when asking for forgiveness. Remember the kindness he provides for those of us who are constantly heedless if His Mesage.Remember the Mercy He has granted us simply being able to ask for forgiveness.

wassalamu alaykum.