“Lailatul Qadr is better than a thousand months” [97:3]
Aisha (Ra) said: “I asked the Messenger of Allah: 'O Messenger of Allah, if I know what night is the night of Qadr, what should I say during it?' He said: 'Say: O Allah, You are pardoning and You love to pardon, so pardon me.''
"Allahumma innaka 'afuwwun tuhibbul 'afwa fa'fu 'annee"
(Ahmad, Ibn Majah, and Tirmidhi).