Question: Can you explain the Sujood of as-Sahu? When do they have to be done after the Tasleem (the Salaam)and when do they have to be done before?
Answer: Sujood as-Sahu (the Prostrations of Forgetfulness) are either performed before Salaam or after Salaam (if you do it after Salaam, then you have to offer another Salaam after the prostrations). Sheikh Muhammad ibn Salih ibn Uthaimeen, may Allah have mercy on his soul, classified this and divided it.
However, before that, we have to know that there are three types of sayings and actions in the prayer: The Pillars, The Mandatory things and The Things that are Sunnah.
1) Examples of the Pillars include reciting Surat al-Fatiha, the standing position, offering Ruku’, offering Sujood, etc. If one forgets a pillar and doesn’t offer it, his prayer is void and must pray again. But if he remembers and offers it while in prayer, his prayer is valid.
2) Examples of the Mandatory things include: the first Tashahhud, if it is a 3 or 4 Rak’ah prayer, saying ‘Subhana Rabbiyal ‘Azeem’ in Ruku’, saying ‘Subhana Rabbiyal Aa’la’ in Sujood, the Takbeers (saying ‘Allahu Akbar’) When moving from one position to another between pillars and saying ‘Sami’ Allahu liman Hamidah’ when rising from Ruku’, etc. If He leaves a mandatory act deliberately, his prayer is void. If he does it out of forgetfulness, he must prostrate for that{Sujood As Sahu}
3) Examples of the Sunan (plural of Sunnah) include: raising the hands when saying Allahu Akbar and Sami’ Allahu liman Hamidah, putting the right palm over the left on the chest, etc. These things are Sunnah; meaning, even if you don’t do them, your prayer is still valid.
Now, there are 4 cases when you have to offer Sujood as-Sahu:
1) Concerning the mandatory things, if you make a mistake in them (such as saying by mistake, ‘Subhaana Rabbiyal A’ala in Ruku’ instead of ‘Subhaana Rabbiyal ‘Azeem’) or forget any of them (such as forgetting to say ‘Allahu Akbar’ when moving from pillar to pillar, for example, when going for prostration), then you offer the Prostrations of Forgetfulness BEFORE the Salaam.
The 2nd case is, if you are in doubt whether you offered it or not and the type of forgetfulness is 50-50. Meaning, for example, I am in prayer and I can’t remember if I prayed 3 Rak’ahs or 4 Rak’ahs; I have no clue whatsoever, I am totally confused and I can’t figure it out; it can be 3, it can be 4. In this case, what is certain is that I have prayed 3 Rak’ahs; the doubt is in the 4th Rak’ah. So, I consider the lesser, which is the certain, of the two choices! I consider that I have prayed 3 Rak’ahs, offer the 4th Rak’ah and then offer the Sujood as-Sahu BEFORE the Salaam.
Therefore, we offer the Sujood as-Sahu BEFORE the Salaam in the above 2 types of cases.
There are 2 other cases for offering Sujood as-Sahu, but this time AFTER the Salaam:
One is when you increase or add something to the Salah. For example, in a 4 Rak’ah prayer, you increase a prostration and prostrated 9 times instead of 8. Or, you add a Tashahhud, sitting in both the 2nd and the 3rd Rak’ahs in a 4 Rak’ah prayer or prayed 5 Rak’ahs instead of 4. In these examples, you have added something to the prayer. In such cases, you prostrate AFTER the Salaam and then offer another Salaam after the prostrations.
The 4th and last case is when I am in doubt, but I have an inclination to one over the other. “Did I pray 3 Rak’ahs or 4 Rak’ahs? Most likely, I prayed 4.” So, I continue with this assumption, say the Tashahhud, complete my prayer with Salaam, then offer 2 Sujood as-Sahu (AFTER the Salaam) and then offer another Salaam. So, it does not matter whether I am inclining to the more or the less; as long as I have my inclination towards 1 of the 2, I complete my prayer accordingly and offer my Sujood as-Sahu AFTER the Salaam and then offer another Salaam.
However, if I am completely confused and I am unable to decide like we mentioned above in the 2nd case, then I consider the lesser of the two, complete my prayer accordingly and offer the Sujood as-Sahu BEFORE the Salaam. For example, when prostrating, I cannot remember at all whether I offered the second prostration or not. So, I neglect the doubt, which is that I have offered the second one, continue and offer another prostration (so that it is definitely 2) and then offer the Sujood as-Sahu BEFORE the Salaam.