In a Hadith on the authority of ‘Aa’ishah, radhiallah ‘anha (may Allah be pleased with her), she said: “I said, ‘O Messenger of Allah, if I know which night is the Night of Al-Qadr, what should I say on that night?’ He said: ‘Say: ‘Allaahumma innaka ‘afuwwun kareemun tuhibbu al-‘afwa fa’fu ‘anni (O Allah, You are Ever Pardoning and Generous and You love pardoning, so pardon me!)’’” [At-Tirmithi: Hasan Saheeh]
In another narration, she said: “I said, ‘O Messenger of Allah, if I witness the Night of Al-Qadr, what should I say?’ He said: ‘Say: ‘O Allah, You are Ever Pardoning and Generous, and you love pardoning, so pardon me.’’” [Ibn Maajah]
Benefits and rulings:
First: The virtue of the Night of Al-Qadr and the keenness of ‘Aa’ishah, the Mother of the Believers, to witness it, offer voluntary prayers in it and supplicate to Allah in it.
Second: The keenness of the Companions to ask about matters that benefit them.
Third: The virtue of supplication on the Night of Al-Qadr and the fact that it is most likely to be answered.
Fourth: A recommendation to supplicate to Allah by the succinct words of the Prophet, sallallaahu ‘alaihi wa sallam, and not to burden oneself with supplications that are rhyming or those whose meanings are not known.
Fifth: The supplication mentioned in the Hadith is one of the most beneficial and all-inclusive supplications because it combines between the good of the worldly life and the Hereafter. For if Allah pardons His slaves in the worldly life, He will remove punishment from them and bestow favor upon them. If He pardons them in the Hereafter, He will save them from Hell and admit them to Paradise.
Sixth: Ascribing the attribute of love to Allah in a way that befits His Majesty and that He The Almighty loves forgiveness.
Seventh: The virtue of pardoning people because Allah The Almighty loves pardoning and those who pardon others.
Eighth: The advice of the Prophet, sallallaahu ‘alaihi wa sallam, to his Ummah (nation) and teaching them what benefits them.
Article source: http://www.islamweb.net/emainpage/