مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٢٢٣ - QIYAM (TO STAND)

person offering prayers that he should ask Divine forgiveness (Istighfar) after Tasbihat Arbaah Forexample, he should say AstaghFirulahha Rabbi wa Atubu ilayhi or he should say Allahummaghfir li. And although he may be busy uttering forgiveness or may have finished it, ifhe doubts before bending himself for bowing whether or not he has recited Surah al-Hamd or Tasbihate Arbaah he should recite Surah al-Hamd or Tasbihat Arbaah.
١٠٢٤. If the person offering prayers doubts in the bowing position of third or fourth unit whether or not he has recited surah al-Hamd, he should ignore his doubt.And if he has doubt before reaching the bowing it is necessary for him to recite Surah al-Hamd or Tasbihat Arbaah
١٠٢٥. If the person offering prayers doubts whether or not he has pronounced a verse or a word correctly eg. whether or not he has uttered Qul Huwallahu Ahadcorrectly he can ignore his doubt. However if he repeats that verse or word correctly as a precautionary measure there is no harm in it. And if he doubts many times he canrepeat many times. However, if he becomes whimsical and utters it once again he should on the basis of recommended precaution offer his prayers de novo.
١٠٢٦. It is recommended that in the first unit the person offering prayers should say Auzubillahi Minash shaytanir Rajim before reciting Surah al Hamd and in thefirst and second units of midday and afternoon prayers he should say Bismillah loudly, should recite Surah al-Hamd and surah distinctly, and should pause at the end of everyverse i.e. he should not join it with the next verse and while reciting Surah al Hamd and surah, should pay attention to the meanings of each verse. And he should say.Alhamdulilahi Rabbil Alamin after the completion of Surah al-Hamd by the Imam if he(the follower) is offering prayers in congregation, and after completion of his SurahalHamd if he is offering the prayers individually.