Abu Hurairah reported,

Abu Hurairah said, "I heard the Messenger of Allah ﷺ say, 'Whoever performs a prayer in which he does not recite the Mother of the Quran, it is deficient, it is deficient, it is deficient, it is incomplete.'"I said, "Abu Hurairah, sometimes I am praying behind the imam."He squeezed my arm and said, "Recite it silently to yourself, Persian, for I heard the Messenger of Allah ﷺ say, 'Allah has said, I have divided the prayer between Myself and My servant into two halves, half of it is Mine and half of it is My servant's, and My servant shall have what he asks for.'"The Messenger of Allah ﷺ said, "Recite! The servant says, 'All praise belongs to Allah, Lord of the worlds' [Fatihah 1:2], and Allah says, My servant has praised Me. The servant says, 'The Most Compassionate, the Most Merciful' [Fatihah 1:3], and Allah says, My servant has extolled Me. The servant says, 'Master of the Day of Judgment' [Fatihah 1:4], and Allah says, My servant has glorified Me. The servant says, 'You alone we worship, and You alone we ask for help' [Fatihah 1:5], and Allah says, This verse is between Me and My servant, and My servant shall have what he asks for. The servant says, 'Guide us to the straight path, the path of those You have blessed, not of those who have incurred Your wrath, nor of those who have gone astray' [Fatihah 1:6–7], and Allah says, These are for My servant, and My servant shall have what he asks for."

عن أبي هريرة يقول

سمعت رسول الله ﷺ يقول: من صلى صلاة لم يقرأ فيها بأم القرآن فهي خداج، هي خداج، هي خداج، غير تمام قال: فقلت يا أبا هريرة! إني أحيانا أكون وراء الإمام، قال: فغمز ذراعي، ثم قال: اقرأ بها في نفسك يا فارسي، فإني سمعت رسول الله ﷺ يقول: قال الله تبارك وتعالى: قسمت الصلاة بيني وبين عبدي نصفين، فنصفها لي ونصفها لعبدي، ولعبدي ما سأل قال رسول الله ﷺ اقرؤوا! يقول العبد {الحمد لله رب العلمين}، يقول الله تبارك وتعالى: حمدني عبدي، ويقول العبد: {الرحمن الرحيم}، يقول الله: أثنى علي عبدي، ويقول العبد: {ملك يوم الدين}، يقول الله: مجدني عبدي، يقول العبد: {إياك نعبد وإياك نستعين} فهذه الآية بيني وبين عبدي، ولعبدي ما سأل، يقول العبد: {اهدنا الصراط المستقيم صرط الذين أنعمت عليهم غير المغضوب عليهم ولا الضالين}، فهؤلاء لعبدي ولعبدي ما سأل.