Tell me all about Sujood as-Sahw (prostration for forgetfulness).

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

It is confirmed that the Prophet sometimes forgot something from the prayer. It is also authentic that he said: "I am a human being and forget like you forget. If I forget, remind me."

There are specific points concerning such prostrations and they are presented below.

How to perform these prostrations of forgetfulness:

The prostration for forgetfulness (Sujood as-Sahw) are two prostrations which a person makes before the Tasleem. All of this was confirmed by the Prophet .

In Saheeh al-Bukhaari, it is reported that Abu Sa'eed al-Khudri narrated that the Prophet said:

“If one of you has some doubts during his prayer and he does not recall (the number of Rak'as) he has prayed, three or four, then he can put an end to his doubt by performing the prayer according to what he was certain of [i.e. the lesser amount] and then perform two prostrations before the Tasleem (saying Salam to conclude the prayer).”

In the story of Thul-Yadayn, reported by Al-Bukhari and Muslim, we are told that the Prophet made the prostrations after the Tasleem.

Ash-Shawkani said: “The best that is stated on this subject is that one must follow what the Prophet said or did, respecting the prostration before or after the Tasleem.

If one does something that necessitates prostration before the Tasleem, he should make them before the Tasleem, and if one does something requiring prostration after the Tasleem, then one should make them after the Tasleem. As for those acts of forgetfulness that are not related to any specific time either before or after the Tasleem, one may choose to make the prostrations before or after the Tasleem in cases of addition or omission in the prayer. This is based on what Muslim reported in his Saheeh from Ibn Mas'ood that the Prophet said: “If one adds or decreases something from his prayer, he should make two prostrations for forgetfulness.’” The Sujood as-Sahw is to be performed in the following circumstances:

1- If a person says the Tasleem before he actually completes the prayer: Ibn Sireen reported that Abu Hurayrah narrated: “The Prophet prayed either Thuhr or ‘Asr prayer with us and he prayed only two Rak'ahs and concluded the prayer with Tasleem. He got up and leaned against a piece of wood in the mosque as if he was angry. He put his right hand on his left and interlocked his fingers. Then, he placed his cheek on the back of his left hand. Some people left the mosque in a hurry, and said: ‘The prayer has been shortened?’ Among the people were Abu Bakr and 'Umar and they were shy to speak to him. One of the people, who was called Thul-Yadayn, said: “O Messenger of Allah! Have you forgotten or has the prayer been shortened?” He answered: 'I have not forgotten and it has not been shortened.' Then he asked: 'Is it as Thul-Yadayn has said?' The people answered affirmatively. Following that, he led the people in what he had forgotten from the prayer and then said the Tasleem. After which he made the Takbeer and prostrated the way he usually prostrated or perhaps even longer. Next, he raised his head and made the Takbeer. Then, he said the Takbeer [again] and prostrated, like one of his customary prostrations or perhaps even longer, and finally, he raised his head.” [Al-Bukhaari and Muslim]

 'Ata' relates thatIbn az-Zubayr prayed Maghrib and said the Tasleem after two Rak'ahs, and then he stood up and wanted to kiss the black stone. When the people tried to correct him he said: “What is the matter with you?” Then he made up what he had forgotten and performed two prostrations. When this was mentioned to Ibn ‘Abbaas, he said that it was not far from the Sunnah of the Prophet.”  [Ahmad, al-Bazzaar, and at-Tabaraani]

2- In the case of an addition to the prayer: In a sound Hadeeth, Ibn Mas'ood narrated that the Prophet prayed five Rak'ahs and the people asked him: “Has there been an addition to the prayer?” He asked: “Why do you say that?” They replied: “You prayed five Rak'ahs.” Then he made two prostrations after he had made the Tasleem. This Hadeeth proves that the prayer of one who prays five Rak'ahs out of forgetfulness, without sitting during the fourth Rak'ahs, is acceptable.

3- In the case of forgetting the first Tashahhud or one of the other Sunnah acts of the prayer: Ibn Buhaynah narrates that the Prophet stood after two Rak'ahs (i.e. without sitting for Tashahhud). The people tried to correct him but he continued. When he finished his prayer, he prostrated two prostrations for forgetfulness and said the Tasleem. This Hadeeth shows that one who forgets the first sitting in Tashahhud but is reminded of it and he recalls it before he completely stands should return and sit, but if he is already completely standing, he should not sit down. This is supported by what Ahmad, Abu Daawood, and Ibn Maajah reported from al-Mugheerah ibn Shu'bah, that the Prophet said: “If one of you stands after two Rak'ahs and he has not completely stood, then he should sit. If he is already completely standing, he should not sit and he should make two prostrations for forgetfulness.”

4- In the case of doubt over whether or not one performed some act of the prayer. 'Abdur-Rahmaan ibn 'Awf reported that he heard the Prophet saying: “If one of you has some doubt during his prayer and he does not know if he prayed one Rak'ahs or two, he should consider that he has only prayed one Rak'ah. If he does not know if he has prayed two Rak'ahs or three, he should consider it as only two Rak'ahs. If he does not know if he has prayed three Rak'ahs or four, he should consider it just as three. [In all such cases] at the end of his prayer, while sitting, he should make two prostrations before the Tasleem.” [Ahmad, Ibn Maajah, and at-Tirmithi] The latter graded it as Saheeh (authentic).

In another narration, it is stated: “Whoever prays and has some doubt that he was short of the complete prayer, he should continue praying until he believes that he has added something to the prayer [with respect to the number of Rak'ahs that he has prayed].”

Abu Sa'eed al-Khudri narrated that the Prophet said: “If one of you has some doubts during his prayer and does not know if he prayed three or four [Rak'ahs], then he should remove his doubt by praying according to the amount that he is certain he had performed and then make two prostrations before the Tasleem. If he had prayed five Rak'ahs, the two prostrations would make it even. If he had prayed a complete four Rak'ahs [when he had finished], they would be in defiance of Satan.” [Ahmad and Muslim]

These two Ahadeeth prove what the majority of the scholars have said; namely, if one has some doubt concerning the number of Rak'ahs he has prayed, he should act according to the amount that he is certain to have prayed (the lesser amount) and then make two prostrations before the Tasleem. [Excerpted from Fiqh as-Sunnah]

Allah knows best.