Professor Hussein Ansarian mentioned in one of his lectures that: The first chapter of the holy Quran is Surah al-Hamad; it is incumbent upon us to recite the Surah al-Hamd in all prayers. There is no problem with whatever Surah we choose to recite after Surah al-Hamad, but if Surah al-Hamad is not recited, then prayer is void. The following narration has been quoted from the Prophet of Islam (pbuh &hp): «لا صلاة الا بفاتحة الکتاب» it means that no prayer is real one without reciting Surah Al-faatehah (THE KEY). In other words, if someone says all his prayers and intentionally avoid reciting Surah al-Hamad, his prayer is not a real prayer and must be said and recited again.
source : erfan.ir
