Abu Hurairah reported,
The Prophet ﷺ said, "Whoever performs a prayer in which he does not recite the Mother of the Quran, it is deficient, it is deficient, it is deficient, incomplete."I said, "Abu Hurayrah, sometimes I am behind the imam."He squeezed my arm and said, "Recite it silently to yourself, Persian, for I heard the Messenger of Allah ﷺ say that Allah the Exalted said, 'I have divided the prayer between Myself and My servant into two halves, half of it is for Me and half is for My servant, 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 all the worlds' [Fatihah 1:2]. Allah 
says, 'My servant has praised Me.' The servant says, 'The Most Merciful, the Most Compassionate' [Fatihah 1:3]. Allah says, 'My servant has extolled Me.' The servant says, 'Master of the Day of Judgment' [Fatihah 1:4]. Allah says, 'My servant has glorified Me.' The servant says, 'Guide us to the straight path, the path of those upon whom You have bestowed favor, not of those who have incurred wrath, nor of those who have gone astray' [Fatihah 1:6–7]. These are for My servant, and My servant shall have what he asks for."
Azami 1965
Sahihعن أبي هريرة
عن النبي ﷺ قال: من صلى صلاة لم يقرأ فيها بأم القرآن فهي خداج، فهي خداج، فهي خداج غير تام. 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 تعالى: قسمت الصلاة بيني وبين عبدي نصفين، فنصفها لي، ونصفها لعبدي، ولعبدي ما سأل. قال رسول الله ﷺ: اقرؤا، يقول العبد: {الحمد لله رب العالمين}، 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: {اهدنا الصراط المستقيم صراط الذين أنعمت عليهم غير المغضوب عليهم ولا الضالين} فهؤلاء لعبدي ولعبدي ما سأل.
Malik narrated it in "Prayer" (39) from Ala bin Abdul-Rahman bin Yaqub, that he heard Abu Saaib, the freed slave of Hisham bin Zahra, say, "I heard Abu Hurairah say," and then he mentioned it.Muslim narrated it in "Prayer" (395) through the route of Malik, but did not give its wording in full. He also narrated it through the route of Sufyan bin Uyayna, from Ala, from his father, from Abu Hurairah, and mentioned the same. Sufyan said, "Ala bin Abdul-Rahman bin Yaqub told me this hadith. I went to visit him while he was ill in his house, and I asked him about it myself."Muslim also narrated it from the hadith of Ibn Jurayj, who said, "Ala bin Abdul-Rahman bin Yaqub informed me that Abu Saaib, the freed slave of the sons of Abdullah bin Hisham bin Zahra, informed him that he heard Abu Hurairah say," the same as the hadith of Sufyan.He says, "In both of their hadiths," meaning the hadith of Malik and Ibn Jurayj, "Allah, the Exalted, says, 'I have divided the prayer between Myself and My servant into two halves, so half of it is for Me and half of it is for My servant.'"As for his saying "khidaj," it means deficiency. Its full form would be "so it is one possessing deficiency," with the noun being described dropped and the possessive noun put in its place, or "so it is deficient," with the verbal noun placed in the position of the object.See Jami al-Usul by Ibn Athir.