Other than normal sujood of Salaah , We have three other prostrations: Forgetfulness(Sahw), Recitation (Tilaawa), and Gratitude (Shukr),
 Sahw Sajda is necessary:
1. When a person forgetfully adds by mistake(i.e the presence of excess by mistake) then the person have to do sahw sajda but if u add something intentionally – the salah becomes invalid or nullified – you have to repeat it.
2. Misses out in his Salaaha a pillar of Salah – bowing, or a prostration, or a standing, or a sitting. In these cases, he or she would have to perform the prostration of Sahw(forgetfulness).So, If u leave out a sunnah – do not perform sahwsajda, but if u leave a wajib ( 1sttashahud in salah) – u perform sahwsajdah, and if you leave out a rukn, you also do sahw, but after making up the unit of prayer that the rukn was missed in. If one noticed only on the second rakah that they missed a rukn i first rakah , in that case first rakah gets void and their second rakah is considered as first. At the end the person have to perform prostration of sahw
3. It is also to be performed if one of the wajib -obligatory actions of Salah is missed forgetfully. For eg: if some one doesnot sit for first tashaahud and gets up and prays third rakah soom after sajdah of second rakah, then that person should conitnue the salaah and peform sujood as sahw at end.
4. If one doubts that he has added or missed any of the abovementioned acts.
And this has two scenarios- 1. You doubt which unit you are praying in 60 – 40 siutaion. 2. You doubt whihc unit you are in , you are 50 – 50 siutation, both cases you need to peform sujood as sahw. In the second scenario, you act upon the lesser amount, i.e. 2 Rak’aat prayed not three. In both scenarios sujood as sahw must be performed.
(the sheikh did not delve into the ‘when’of the sujood- and left you with the view of the author stating there is a difference of opinion regarding the matter)
As per Shk Sa’d ” In case if some one say subhana Rabbil A’la whilst in rukoo and Subhana rabbail A’dheem in Sujood, has indeed made a mistake. But if then he/she did this mistake is out of forgetfulness and unintentional it does not affect their salaah – it is from the verbal obligatory actions and they are active obligations. Whoever makes mistake (out of forgetfulness) of verbal obligation then it does not consitute the necessitate to perform sujood as sahw.” (Taken from 57th min of recorded lecture 5)
– It is affirmed from the Prophet (s) that he once missed out the first Tashahhud and thus performed the prostration of Sahw.
– Also, he (s) once made the Tasleem after having prayed two Rak’ahs for Dhuhror ‘Asr, and then realized what he had done, and therefore completed them and performed the prostration of Sahw.
– Also, he (s) once prayed Dhuhras five Rak’ahs. He was asked: “Have you increased the Salah?” He (s) said: “What makes you say that?” He(s) was told: “You prayed five.” He therefore prostrated twice, havingalready done the Tasleem. [Agreed Upon]
The Prophet (s) said: “If any one of you is in doubt about hisprayer and he does not know how much he has prayed, whetherit is three or four (Rak’ahs), then he should cast aside his doubtand consider having prayed (the number) that he is certain of,then perform two prostrations before making the Tasleem. If hehas prayed five Rak’ahs, then these will make his prayer aneven number for him, and if he has indeed prayed four, thenthey will be humiliation for the devil.” [Muslim]
 The one performing the prostration of Sahwcan do so beforeor after the Tasleem. (There is a difference of opinion – Specific circumstances before or after tasleem)
The Prostration of Tilaawah (Recitation)
 The prostration of Tilaawah(recitation) is recommended(Sunnah) for the person reciting (the Qur’an) as well as the onelistening (to the recitation) both,
- · Reciting In the Salaah – do takbeer then sajda and takbeer again for standing up.
- · Reciting Out of Salaah – (correct view not required to say the takbeer and not even coming out of sajdah but peform sajdah immediately).
- · Some ulamaa say sijda at-tilaawah occurs 14 places in Quran, other say 15.
- · Make sajda after reciting that particular verse. In sajda say “subhanrabbiyal ‘ala” – 3 or 10 times.
Do we have to do wudu for sajdah Tilawah, the first view is of 4 imams that once must have wudu to practise this sujood, second view of ibn umar and group that agreed with thim who said that this particular sujood does not constiute salaah so can practised without wudu. This is the correct view and view of Shk Sa’d.
Who are those that prostrate?
- · The reciter
- · The listener with intent, concentration and desire – the one who is listening and pondering over its meaning, not the one who passes by and hear the Quran recited, or hears it in the background – but not listening to it.
Shaikh quotead a hadith which says when the son of Adam prostrate, shaitan goes into seclusion and says “woe unto me”. the son of Adam was commanded to and did and I (Shaitan) was commanded to make sujood but did not prostrate.
The Prostration of Gratitude (Shukr)
 If a person is bestowed with a blessing or has been saved froma calamity; he should prostrate to Allah in gratitude,
 and theruling for this prostration is the same as that of the prostration ofTilaawah.
Source: Taken from Course-Lecture4: by Shaikh Saad ibn Naasir Al Shithry, a former member of the Senior Scholars’ Council of Saudia Arabia and the Vice-President of KIU based on the book ’Manhaj As Salikin’ (The Methodology of the Traveller and a Clarification of Fiqh of the Religion) by Shaikh Abdur -Rahman As-Sa’di.