The Messenger of Allah (ﷺ) said to al-Abbas ibn AbdulMuttalib: Abbas, my uncle, shall I not give you, shall I not present to you, shall I not donate to you, shall I not produce for you ten things? If you act upon them, Allah will forgive you your sins, first and last, old and new, involuntary and voluntary, small and great, secret and open.
These are the ten things: you should pray four rak'ahs, reciting in each one Fatihat al-Kitab and a surah. When you finish the recitation of the first rak'ah you should say fifteen times while standing: "Glory be to Allah", "Praise be to Allah", "There is no god but Allah", "Allah is most great". Then you should bow and say it ten times while bowing. Then you should raise your head after bowing and say it ten times. Then you should kneel down in prostration and say it ten times while prostrating yourself. Then you should raise your head after prostration and say it ten times. Then you should prostrate yourself and say it ten times. Then you should raise your head after prostrating and say it ten times in every rak'ah. You should do that in four rak'ahs.
If you can observe it once daily, do so; if not, then once weekly; if not, then once a month; if not, then once a year; if not, then once in your lifetime.
Sunan Abi Dawud Book 5, Hadith 48
I never heard `Umar saying about something that he thought it would be so-and-so, but he was quite
right. Once, while `Umar was sitting, a handsome man passed by him, `Umar said, "If I am not wrong,
this person is still on his religion of the pre-lslamic period of ignorance or he was their foreteller. Call
the man to me." When the man was called to him, he told him of his thought. The man said, "I have
never seen such a day on which a Muslim is faced with such an accusation." `Umar said, "I am
determined that you should tell me the truth." He said, "I was a foreteller in the pre-lslamic period of
ignorance." Then `Umar said, "Tell me the most astonishing thing your female Jinn has told you of."
He said, "One-day while I was in the market, she came to me scared and said, 'Haven't you seen the
Jinns and their despair and they were overthrown after their defeat (and prevented from listening to
the news of the heaven) so that they (stopped going to the sky and) kept following camel-riders (i.e.
'Arabs)?" `Umar said, "He is right." and added, "One day while I was near their idols, there came a
man with a calf and slaughtered it as a sacrifice (for the idols). An (unseen) creature shouted at him,
and I have never heard harsher than his voice. He was crying, 'O you bold evil-doer! A matter of
success! An eloquent man is saying: None has the right to be worshipped except you (O Allah).' On
that the people fled, but I said, 'I shall not go away till I know what is behind this.' Then the cry came
again: 'O you bold evil-doer! A matter of success! An eloquent man is saying: None has the right to be
worshipped except Allah.' I then went away and a few days later it was said, "A prophet has
appeared."
Sahih al-Bukhari Book 63, Hadith 91
"Abu Al-Mutawakkil passed by them in the market and some people, including me, stood up to greet him. We said: 'We have come to you to ask you about transactions.' He said: 'I heard a man say to Abu Saeed Al-Khudri': 'Is there anyone between you and the Messenger of Allah (in the chain of narrators) apart from Abu Saeed Al-Khudri? He said: 'There is no one else between him and I. He said: Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, salt for salt, equal amounts. Whoever gives more than that or takes more has engaged in Riba, and the taker and the giver are the same."'
Sunan an-Nasa'i Book 44, Hadith 117