The recitation of Umm-ul-Quran (Al-Fatihah) is obligatory in prayer

 281. Abu Hurairah narrated that the Prophet salla alayhi wa sallam said: ´´He who performs Salat (prayer) in which he does not recite Umm-ul-Qur´an, (i.e., Al Fatihah) it is deficent [he said this three times] and  not complete.´´ It was said to Abu Hurairah: ´´At times we are behind the Imam.´´ He said: ´´Recite it inwardly, for I heard the Messenger of Allah salla alayhi wa sallam declare that Allah had said: ´I have divided the prayer into two halves between Me and My slave, and My slave will receive what he asks for.´ When the slave says: ´Praise be to Allah, the Rubb of the worlds,´ Allah says: ´My save has praised me.´ And when he says: ´The Most Gracious, the Merciful,´ Allah says: My slave has lauded Me.´ And when he says: Owner of the Day og Requital,´ He remarks: ´My slave has glorified Me,´ and sometimes He would say: ´My slave committed (his affairs) to Me.´ And when he (the slave) says: ´You (Alone) do we worship and from You do we seek help,´ He says: ´This is between Me and My slave,´ and My slave will receive what he asks for.´ Then, when he (the slave) says: ´Guide us to the Straight Path, the path of those on whom You have bestowed Your grace, not of those who have incurred You wrath, nor of those who have gone astray,´ He says: ´This is for My slave, and My slave will receive what he asks for.´´´