The prostration for forgetfulness (Sajdah Sahw) is made when there is any delay of an obligatory act (fardh) or an omission or delay of a required act (Wajib) in performance of a prayer, such as forgetting to recite Fatiha in any prayer, reciting the surah before the Fatiha, forgetting to recite the supplication of Witnessing (at-Tahiyyatu) in the first and second sitting etc.

How The Perform A Prostration For Forgetfulness (Sajdah Sahw)

Recite the Supplication Of Witnessing (at-Tahiyyatu) in the last sitting at the and of a ritual prayer, make the salutation first to the right then to the left and then immediately prostrate with the utterance of takbir "Allah-u Akbar". We then make two successive prostrations as we do in each rakat of a ritual prayer. Afterwards, we recite the supplications of Witnessing Allahumma Salli, Allahumma Barik and Rabb'ana, and then we again make the salutation (Salaam).