Sajda al-sahw in the remaining part of the masbuq’s prayer

Question

A masbuq caught two rak‘as of a four-rak‘a prayer. If, while praying his remaining two rak‘as, he made some error through forgetfulness, will he have to perform sajda al-sahw, or will the prayer be fulfilled without sajda al-sahw?

Answer

If such an error occurs after the imam has given the salam, while he is completing the remainder of his prayer, sajda al-sahw will be binding. Without sajda al-sahw the prayer will remain deficient.

Source: Fatawa Mahmudiyya

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