اللهم إنك عفو تحب العفو فاعفو عنى
Allahumma innaka `afuwwun, tuhibbul-`afwa, fa`fu `anni
O Allah, You are Most Forgiving, and You love forgiveness; so forgive me.
This is the famous du’aa to be made while seeking laylatul qadr (the night of decree which is one of the last 10 nights of Ramadan). Remember, this was given by the Prophet (peace be upon him) to one of the most beloved of all people to him: Aisha (radi’allahu anhaa) when she asked him what du’aa to make in this time (Sunan at Tirmidhi and others). So that makes the du’aa extra special. Some other things that make this du’aa special:
‘afoo means to wipe away without a trace and to have leftovers/to prosper, meaning the sins will not be mentioned on the day of judgement, as if you never committed them (unlike maghfirah which means to forgive the sin but it will still be documented and presented to you on the day of judgement).
Al-’Afuw is one of the majestic names of Allah.
Recite this du’aa as much as you can! Especially in these last days of Ramadan.