Liaison office of Grand Ayatullah Sayyid Ali Al Sistani (L.M.H.L) in London, Europe, North and South America.
1202. If a person doubts about the number of Rak'ats in a Mustahab
prayer and if the higher side makes the prayers void, he should decide on the
lesser side of the doubt. For example, if he doubts whether he has performed 2
Rak'ats or 3 in Nafilah of Fajr prayers, he should decide that he has performed
2 Rak'ats. But if the higher side does not invalidate the prayers, like, if he
doubts whether he has performed 2 Rak'ats or 1, he is free to decide either way,
and his prayers will be valid.
1203. Omission of a Rukn invalidates Nafilah (Mustahab prayers), but
addition of a Rukn does not invalidate it. Hence, if the person offering Nafilah
prayers forgets to perform any part, and remembers when he has entered into
another Rukn, he should return to perform the forgotten part and then re-enter
the Rukn. For example, if he remembers during Ruku that he has not recited Surah
al-Hamd, he should return to recite Surah al-Hamd, and then go into Ruku again.
1204. If a person doubts whether he has performed any Rukn or non-Rukn
part of Nafilah prayers, he should perform it if its stage has not passed, and
if it has, then he should ignore the doubt.
1205. If in a Mustahab prayer of two Rak'ats, a person suspects that
he has offered 3 Rak'ats or more, he should ignore his doubt, and his prayers
are in order. If, he suspects that he has offered 2 Rak'ats or less, then as an
obligatory precaution, he should pay heed to that suspicion. For example, if he
suspects that he has performed one Rak'at only, as a precaution, he will perform
another Rak'at.
1206. If a person in Nafilah prayers performs an act which, if he had
performed in an obligatory prayers, it would have been necessary for him to do
Sajdatus Sahv, or if he forgets one Sajdah, it will not be necessary to perform
Sajdatus Sahv, or give qadha for the Sajdah, after the Nafilah is over.
1207. If a person doubts whether he has offered a particular Mustahab
prayer or not, and if that prayer does not have a fixed time, like, the prayers
of Ja'far Tayyar, he should decide that he has not offered it. The position is
the same if that prayer has a fixed time, like Nafilah of daily prayers, and a
person doubts before its time lapses, whether he has offered it or not. However,
if he doubts after its time has gone, he should ignore his doubt.