Sahw means forgetfulness or to omit something unconsciously. Sajda al-sahw means two prostrations performed due to the omission of something that is a wajib part of the prayer. An example: One is praying a prayer of 3 or 4 units (rak’ahs). It is wajib to sit (the tashahhud position) in the second rak’ah before standing up to perform the third rak’ah. If one forgets to sit in the second rak’ah and stands up for the third rak’ah without it, one must perform sajda al-sahw as a compensation for the omission of this sitting position, which was wajib. Sajda al-sahw applies to all types of prayer, i.e. fard, wajib, sunnah and nafl.

Sajda al-sahw is performed in the last rak’ah (third or fourth, depending on whether one prays 3 or 4 units). It can be performed either after only one slam to the right or after salam to both sides. One can also choose between reciting only tashahhud or both tashahhud, durud sharif and dua before making salam. However, the most preferred is to do it after only one salam to the right, and to recite only tashahhud before making salam. After making salam in this way, one performs two sajdas in the usual way. And then one remains in the tashahhud position, recites both tashahhud, durud sharif and dua, and completes the prayer in the usual way.

This does not apply if one is praying in congregation (with the imam) and makes a mistake that requires sajdah al-sahw. There is no sajdah al-sahw in this case. However, if the imam makes such a mistake and performs sajdah al-sahw, it is important for everyone praying behind that imam to follow him.

And Allah knows best.

Wassalam

Najeeb Naz