Hadith : If you pray Salat Al Tasbeeh prayer Allah will forgive your first and last, old and new, small and great sins , If you can not observe it daily then read every Friday Weekly

Bismillahirrahmanirrahim 

Hadith : If you pray Salat Al Tasbeeh prayer Allah will forgive your first and last, old and new, small and great sins , If you can not observe it daily then read every Friday Weekly
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Narrated Abdullah Ibn Abbas radi allahu anhu: The Apostle of Allah (peace_be_upon_him) 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 Surah Fatiha and a surah. When you finish the recitation of the first rak'ah you should say fifteen times (15) while standing: 

سبحان الله والحمد لله ولا اله الا الله والله أكبر

Subhnallahi Walhamdulillahi Wa la ilaha illallahu wallahu Akbar 

("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 (10) times while bowing. 

Then you should raise your head after bowing and say it ten (10) times. 

Then you should kneel down in prostration and say it ten (10) times while prostrating yourself. 

Then you should raise your head after prostration and say it ten (10) times. 

Then you should prostrate yourself and say it ten (10) times. 

Then you should raise your head after prostrating and say it ten (10) times in every rak'ah. 

(in this way it will be total 75 times in a rakah)

You should do that in four rak'ahs. 
If you can observe it once daily, do so; 
if not, then once weekly Friday; 
if not, then once a month;
 if not, then once a year; 
if not, then once in your lifetime.

Sunan Abu Dawud: Book 5, Number 1292- Sahih

Sunan Ibn majah Book 5, Hadith 1387 - Hasan

Arabic text ( Sahih Sanad)

http://www.sunnah.com/abudawud/5/48

http://www.sunnah.com/urn/1287350