Meaning


The Arabic word for prostration is ‘sajdah.’ It means to put one’s head, hands, knees, and toes on the ground. The two sajdahs made at the end of salah to make up for major errors are known as the ‘prostration of forgetfulness’ or sajdah as-sahw in Arabic.

Importance


We human beings are forgetful by nature and even forget when we are praying to Allah. Our Creator is well aware of that fact and He made His Prophet, may the mercy and blessings of Allah be upon him, forget on some occasions in the prayer. This way the Prophet showed us how to correct our mistakes in the prayer. Making up for our mistakes in prayer is a great mercy from Allah because He could have made us repeat the prayer for every mistake, but He did not.

When Are Prostrations of Forgetfulness Required?


They are two occasions when they are required:

I.    When you add or subtract to the acts of salah.

Examples of addition:

You pray 5 rakahs instead of 4.

You do three prostrations instead of two.

You make tashahhud at the end of first rakah.

Example of subtraction:

You pray 3 rakahs instead of 4.

You do one sajdah instead of two.

You get up for the third rakah without doing the first tashahhud.

II.    When you forget the number of rakahs and are in doubt, (for example) whether you prayed three of four rakahs.

Missing a Rukn (Essential Component or Pillar of Salah)


If you omit the Takbiratul-Ihram, then there is no prayer for you, regardless of whether you left it intentionally or due to forgetfulness, because you never started the prayer.

If you omit a rukn other than the Takbiratul-Ihram deliberately, your salah is invalid.

If you left a rukn out of forgetfulness and you reached the next rakah, then the rakah in which you left the rukn is invalid and the following rakah takes its place.

If you did not reach the next rakah, you must return to the rukn you omitted and perform it and follow it by what comes after it in the course of the salah.

In both of the above situations, you offer the “prostration of forgetfulness”.

Missing a Wajib (Obligatory act of salah)


If you leave out something wajib unintentionally, like the first tashahhud or a prostration, you simply do sajdah as-sahw at the conclusion of prayer.  However, it is left intentionally, then the prayer is invalid.

Missing a Recommended Act in Prayer


You do not have to make the “prostration of forgetfulness” if you forget to perform one of the recommended acts of prayer.

Method of Sajdah as-sahw


You have a choice between two ways of doing it:

1.    Immediately before tasleem at the end of salah.

Before concluding the prayer with tasleem, you say Allahu Akbar, and then make the first prostration.

In the prostration you say, Subha-na Rabbi al-A'la three times. Then you say Allahu Akbar and return to the sitting position.

Then you say Allahu Akbar again and make the second prostration and say the same words as you did in the first prostration.

You then say Allahu Akbar for the last time, return to the sitting position, and turn your head to the right and then to the left, saying each time “As-Salamu 'Alaikum wa-Rahmatullah.”

2.    Doing it after tasleem.

Another way is to continue your salah and end it with tasleem as you normally would.

After that you say Allahu Akbar and prostrate for your first prostration, and say Subha-na Rabbi al-A'la three times. Then you say Allahu Akbar and return to the sitting position.

Then you say Allahu Akbar again and do your second prostration and say Subha-na Rabbi al-A'la three times.

Finally, you say Allahu Akbar the last time and return to the sitting position, and then turn your face to the right saying “As-Salamu 'Alaikum wa-Rahmatullah.”

Further Notes/Examples


1.    If you realize before making tasleem that you have added anything to the salah, for example an extra rakah, you may do sajdah as-sahw before or after tasleem.

2.    If you did not pray one or more rakah, you must get up and complete them, then at the conclusion of prayer you do sajdah as-sahw.

3.    If you forgot to perform sajdah as-sahw, but remembered shortly afterwards, then you should do it as soon as you remember it.  However, if a long time has passed, then you do not have to do anything and your prayer is still valid. 

4.    If the Imam offers sajdah as-sahw, everyone else behind him also does it, even if no individual made a mistake.

5.    If you make a mistake behind an Imam, you do not offer your own sajdah as-sahw because the Prophet said, “Indeed, the Imam was made to be followed.”[1]

6.    What do you do it you are uncertain about how many rakahs you have prayed? You assume and go by the number you are more certain of.  For example, in a four rakah prayer, you think you more likely prayed three rakahs, then you pray another one and do sajdah as-sahw. If you think you prayed four rakahs, all you do is do sajdah as-sahw at the end. If you are unable to decide which of the two is more probable, it could have been three or four rakahs, you assume and go by the lesser count, i.e. three rakahs. You pray another rakah and then do sajdah as-sahw.