Sunan Ibn Majah Book 34, Hadith 23
he heard Abu Bakr, when the Prophet (saas) had passed away, saying: "The Messenger of Allah (saas) stood in this place where I am standing, last year." Then Abu Bakr wept, then he said: "You must adhere to the truth, for with it comes righteousness and they both lead to Paradise. And you must beware of lying for with it comes immorality, and they both lead to Hell. Ask Allah for Al-Mu'afah, for no one is given anything after certainty that is better than Mu'afah. Do not envy one another, do not hate one another, do not sever ties with one another, do not turn your backs on one another and be, O slaves of Allah, brothers."
"A man come to the Prophet (saas) and said: 'O Messenger of Allah, what supplication is best?' He said: 'Ask your Lord for forgiveness and to be kept safe and sound in this world and in the Hereafter.' Then (the man) came the next day and said: 'O Messenger of Allah, what supplication is best?' He said: 'Ask your Lord for forgiveness and to be kept safe and sound in this world and in the Hereafter.' Then (the man) came the third day and said: 'O Prophet of Allah, what supplication is best?' He said: 'Ask your Lord for forgiveness and to be kept safe and sound in this world and in the Hereafter, for if you are forgiven and kept safe and sound in this world and the Hereafter, you will have succeeded.'"
"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).'"