(11) باب وُجُوبِ قِرَاءَةِ الْفَاتِحَةِ فِي كُلِّ رَكْعَةٍ وَإِنَّهُ إِذَا لَمْ يُحْسِنِ الْفَاتِحَةَ وَلاَ أَمْكَنَهُ تَعَلُّمُهَا قَرَأَ مَا تَيَسَّرَ لَهُ مِنْ غَيْرِهَا
Ubada b. as-Samit reported:
The Messenger of Allah (ﷺ) said: He who does not recite Umm al-Qur'an is not credited with having observed the prayer. (ID)
Reference (ID): Sahih Muslim 394 b (ID)
In-book reference (ID): Book 4, Hadith 38 (ID)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 772 (ID)