It Is Obligatory To Recite Al-Fatihah In Every Rak'ah; If A Person Cannot Recite Al-Fatihah Or Cannot Learn It, Then He Should Recite Whatever Else He Can Manage Sahih Muslim 397 b
Translation
Abu Huraira reported
A person entered the mosque and said prayer while the Messenger of Allah (ﷺ) was sitting in a nook (of the mosque), and the rest of the hadith is the same as mentioned above, but with this addition:" When you get up to pray, perform the ablution completely, and then turn towards the Qibla and recite takbir (Allah o Akbar =Allah is the Most Great)."