Liaison office of Grand Ayatullah Sayyid Ali Al Sistani (L.M.H.L) in London, Europe, North and South America.
1114. While a person sits after reciting tashahhud in the last Rak'at,
and his body is tranquil, it is Mustahab to say: Assalamu 'alayka ayyuhan
Nabiyyu wa rahmatullahi wa barakatuh.
Then he should say: Assalamu Alaykum
and as a recommended precaution add to it Wa Rahmatullahi Wa Barakatuh.
Alternatively, he can say: Assalamu Alayna Wa Ala Ibadi llahis Salihin. But if
he recites this Salam, then as per obligatory precaution, he must follow it up
with saying: Assalamu Alaykum.
1115. If a person forgets the salam of prayers, and remembers when the
form of namaz has not be disrupted, nor has he performed any act, which if done
intentionally or forgetfully, invalidates the prayers (e.g. turning away from
Qibla), he should recite the salam and his prayers will be valid.
1116. If a person forgets the salam of prayers, and remembers after
the form of prayers has been disrupted, or after he has performed an act which
if done intentionally or forgetfully, invalidates the prayers (e.g. turning away
from Qibla), his prayers are in order.