Salam alikom,
It's sunnah and not fard (obligatory), so you don't actually have to do it. However, basically if you make any mistakes in the salah (such as missing a unit of prayer, or doing soujoud once instead of twice...) and you do realise that you did that mistake, then it's good to do the two prostrations of forgetfulness at the end.
Wa `alaykum salaam wa rahmatullaah
Brother I advise you to not speak without knowledge- unless you are backing up your statement with proof and views of the scholars. Can you tell me which scholar said that Al-Sajdah al-Sahw is Mustahabb? What is sunnah is the discussion as to *when* to do the sajdah. The scholars differ as to whether the sajdah is to be done before or after the taslaam (salaam).
As for brother Islam... then to keep it as brief as possible:
- If you add/omit a
pillar (out of forgetfulness) in Salaah, then you do the prostrations after the Tasleem (Salaam), and after the two prostrations you say salaam again.
If you added, then you discontinue that pillar and return back to where you are meant to be. Ex: If you stand up for the 5th rak`ah, and then you realize that you stood up for a 5th rak`ah in a 4 rak`ah prayer.. then you immediately go down to tashahhud, recite your tashahhud and at the end- you say salaam and do the prostrations followed by another salaam.
If you omitted a pillar and you went to the next pillar- you go back and perform the pillar you omitted. Ex: You remember, after standing up for the 2nd rak`ah, that you forgot to do the 2nd sajdah in the first rak`ah. Then as soon as you remember, you go back and do the 2nd sajdah and then you carry on praying your salaah from 2nd sajdah.
- If you omit the
first Tashahhud (out of forgetfulness) in a salaah that has
two tashahhud, then you do the prostrations before the tasleem.
In the above cases, the prostrations are obligatory.
However, if you were to do the prostrations before the tasleem for any mistake you make in your salaah- whether the mistake is in the pillars or the obligator actions... then this is acceptable. As to
when to do the prostrations is disputed by the scholars and is an open matter.
Below are a list of the pillars of Salaah (taken from an article):
The Arkaan (Pillars) of Salaah are Twelve:
1)
Qiyaam – Standing up for prayer. Thus, the one who does not stand up for Salaah, without excuse, for obligatory prayers, his Salaah is invalid.
2)
Takbeeratul-Ihraam – Takbeer is to say: Allahu Akbar. Takbeeratul-Ihraam is the first Takbeer with which one enters the Salaah, and so it is a Rukn of Salaah, unlike the rest of the Takbeeraat of Salaah
3)
To recite Soorah al-Faatihah
4)
Rukoo'. That is to bow. The perfection of Rukoo' is achieved by placing ones hands on the knees, grabbing them, while the back is straight and the head in level with the rest of the back, and the elbows away from the sides. To fulfil the obligation of Rukoo' is for hands to touch the knees.
5)
Standing up after Rukoo'. This is until one’s back is straight. If one stands up in hurry, and does not straighten his back, then he misses out on a Rukn, which makes that rak’ah invalid.
6)
Sujood. That is, to Prostrate. The perfection of Sujood is achieved by placing the hands in level with the shoulders with fingers joined together, while spacing out between the elbow and the sides, as well as between the thighs and the stomach. The obligation in Sujood is to prostrate on seven limbs: 1) The forehead and the nose, 2 & 3) the two hands, 4 & 5) the two knees, 6 & 7) the toes placed on ground facing the Qiblah. Thus, if any of these limbs are not on the ground, it renders the Sajdah to be invalid.
7)
To sit between two Sajdahs. While in the position of Iftiraash: Which is to sit on one’s left leg, while the right foot is perpendicular to the ground, and the toes are facing the Qiblah.
8)
To be tranquil in all the Arkaan.
9)
The last Tashahhud. Tashahhud is to say: at-Tahiyaatu liLlaahi was-Salaatu wat-Tayyibaat… to his words: wa Ash-hadu anna Muhammadan 'Abduhu wa Rasooluh.
10)
Sitting for the last Tashahhud. This is regarded to be a Rukn in itself, because it is possible that one may begin reciting Tashahhud, during the process of getting up from Sujood, but before sitting for it, in which case, his Salaah is invalid, because he missed out on the Rukn of 'sitting for Tashahhud'. If the Salaah only has one Tashahhud, like Salaatul-Fajr, then one sits in the position of Iftiraash, which has been described above. If Salaah contains two Tashahhud, like Dhuhr, 'Asr, Maghrib and 'Ishaa' then one sits in the Tawarruk position whilst in the final tashahhud, which is to sit on one’s left thigh, while exiting both feet from the right side, making the right foot perpendicular to the ground, and the toes facing the Qiblah.
11)
To end the Salaah with Tasleem, which is to say as-Salaamu 'Alaikum wa-raHmatullah, by turning ones head to the right first, and then to the left.
12)
Performing these Arkaan, in the order mentioned above. Thus, one may not perform Rukoo' before Sujood and so on. For example: If one forgets to make Rukoo' after al-Faatihah, but goes straight into 'standing up after Rukoo', and then remembers in the second Sajdah of the same Rak'ah that he forgot to make Rukoo', then he should get up from Sujood, immediately, and perform Rukoo' which he missed, and then perform all the usual Arkaan and Waajibaat that come after Rukoo'.
These are the twelve Arkaan of Salaah. If one leaves them intentionally or unintentionally, the Salaah is rendered invalid. One is obliged to perform the missed Rukn, as the Sajdah as-Sahw is not enough to replace it.
But, how am I supposed to remember it all?!
One can commit these Arkaan to his memory by doing three things:
i) Remember, that most of the Arkaan are the most visibly apparent actions of Salaah, such that an onlooker can tell whether the one praying has missed out a Rukn or added to it. For example, standing up for Salaah, or performing Rukoo', or standing up after it, or performing Sujood etc.
ii) Remember the number, that they are 12, no more and no less.
iii) Remind yourself of the Arkaan, with the help of the above two points. So you set yourself a target of remembering 12 most apparent actions of Salaah, then begin counting from the first Rukn, which is Qiyaam, till the last, which is the order of Arkaan.
So just think, what is the first thing you do in Salaah?
Answer: You stand up.
Therefore, Standing up for Salaah is the first Rukn.
Then what do you do?
Answer: You say: Allaahu Akbar, thus, the second Rukn.
This is how you keep reminding yourself of the rest of the Arkaan, until you are able to count all 12 of them.
Obviously, not all of the Arkaan are most visibly apparent, like Takbeeratul-Ihraam or al-Faatihah, the last Tashahhud, but the secret of ease in remembering all the Arkaan lies in the fact that the invisible Arkaan are only three. Likewise, not all of the most visibly apparent actions of Salaah are Arkaan, rather some of them are Waajibaat, while others are only Sunan acts, for example; reciting al-Faatihah aloud in aloud prayers, or reciting a Soorah after al-Faatihah in the first two Rak'ahs, placing the right hand over the left in Qiyaam, or raising the hands, etc are from the Sunan, recommended actions of Salaah, and not from the Arkaan nor the Waajibaat of Salaah.
Another thing to remember with regards to Tashahhud, whether it is the middle one (which is a Waajib), or the last one (which is a Rukn as we said), is that whenever Tashahhud is mentioned, whether in Arkaan or Waajibaat, it is instantly followed by 'Sitting for Tashahhud'. Thus, only by remembering one Rukn/Waajib of Tashahhud, you should automatically remember the next Rukn/Waajib which goes with it, which is to sit for Tashahhud.