"So know (O Muhammad) that there is no God save Allah, and ask forgiveness for thy sin and for believing men and believing women. Allah knoweth (both) your place of turmoil and your place of rest."
 

(Holy Qur'an (Pickthall) 47:19)

"Then have patience (O Muhammad). Lo! the promise of Allah is true. And ask forgiveness of thy sin, and hymn the praise of thy Lord at fall of night and in the early hours."
 

(Holy Qur'an (Pickthall) 40:55)

"If you have the same knowledge of things about life after death, things which are hidden from you and revealed to me, the information would have made you leave your hearth and home and to disperse in the world weeping over your sins, putting yourself to torture for the evil deeds committed by you and leaving your wealth and property in such as way that there will be no one to look after it and none to inherit it. The apprehension about the future and the remorse over the past would have so affected every one of you that nobody would have had time to think of anything besides his own future.
 
But you have forgotten what has been taught to you and (wrongly) believe yourself to be well protected from the things of which you were warned. The result is that your plans are upset and your affairs are confused.
 
I pray to God to separate me from you and to let me have the company of those who merited my companionship and whose company I deserve. By God, there were people who maintained a very sober and serious view about life. They were patient and human towards people. They were truthful and honest. They have given up evil ways of life. They were foremost in sincerely accepting Islam, always followed the true path and dying as true Muslims they succeeded in achieving high positions in heavens."
 

(Nahjul Balagha: Sermons, letters and saying of Hazrat Ali (Second American edition, 1981), Khutba 119, p. 89