Hazrat Abu Hurairah radiyallahu anhu reported Allah’s Messenger sallallahu alaihe wasallam as saying, “If anyone observes a prayer in which he does not recite Umm-ul Qur’aan, it is deficient (he said this three times) and incomplete.”
When someone said to Abu Hurairah radiyallahu anhu that we remain behind the Imaam, he replied, “Recite it inwardly,” for he had heard Allah’s Messenger sallallahu alaihe wasallam declare that Allah Most High had said, "I have divided the prayer into two halves between Me and My servant, and My servant will receive what he asks.’
When the servant says, ‘Praise be to Allah Lord of the Universe.’
Allah most high says, ‘My servant has praised Me.’
When he says, ‘The Compassionate the Merciful.’
Allah most high says, ‘My servant has lauded Me.’
When he says, ‘Possessor of the Day of Judgement.’
He says, ‘My servant has glorified me,’
When he says, ‘Thee do we worship and of Thee do we ask help.’
He says, ‘This is between Me and My servant, and My servant will receive what he asks.’
Then when he says, ‘Guide us in the straight path, the path of those whom thou hast favoured; not of those with whom Thou art angry nor of those who go astray.’
He says, ‘This is for My servant, and My servant will receive what he asks."
- Hazrat Abdul Malik ibn Umair radiyallahu anhu reports that Rasoolullah sallallahu alaihe wasallam said, “In Surah Fatihah there is a cure for all ailments.”