Narrated Abdullah Ibn Abbas:
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 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.