If a person says al‑tasbīḥāt al‑arbaʿah in the first two rakʿahs of prayers thinking that he is performing the last two rakʿahs, in the event that he realises this before rukūʿ, he must recite Sūrat al-Ḥamd and the other surah. If he realises this during or after rukūʿ, his prayer is valid.