(11) باب وُجُوبِ قِرَاءَةِ الْفَاتِحَةِ فِي كُلِّ رَكْعَةٍ وَإِنَّهُ إِذَا لَمْ يُحْسِنِ الْفَاتِحَةَ وَلاَ أَمْكَنَهُ تَعَلُّمُهَا قَرَأَ مَا تَيَسَّرَ لَهُ مِنْ غَيْرِهَا
Mahmud b. al-Rabi', on whose face the Messenger of Allah (ﷺ) squirted water from the well, reported on the authority of 'Ubada b. as- Samit that the Messenger of Allah (ﷺ) said:
He who does not recite Umm al-Qur'an is not credited with having observed prayer. (RU)
Reference (RU): Sahih Muslim 394 c (RU)
In-book reference (RU): Book 4, Hadith 39 (RU)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 773 (RU)