Sunan Ibn Majah

It was narrated from 'Aishah that she said:""O Messenger of Allah, what do you think I should say in my supplication, if I come upon Laylatul-Qadr?"" He said: ""Say: 'Allahumma innaka 'afuwwun tuhibbul-'afwa, fa'fu 'anni (O Allah, You are Forgiving and love forgiveness, so forgive me)