What should one do if he erred in his prayer and did not know how many rak'ahs he had prayed, so he based it on the minimum, then became certain in the fifth rak'ah that his assumption was incorrect: should he continue with the fifth rak'ah and perform the prostration of forgetfulness, or should he cut it short for the tashahhud, or should he repeat the prayer?
The worshiper must sit immediately upon remembering that the rak'ah he is performing is the fifth. It is not permissible for him to complete it, nor should he interrupt his prayer and repeat it. He should perform the prostration of forgetfulness ( sujud al-sahw) at the end of his prayer for the addition he made.
Summarized from the full answer at Ftawy · reviewed Sep 2, 2026
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