the Prophet said: "There is no Salat for the one who does not recite Fatihatil-Kitab."
Jami` at-Tirmidhi Book 2, Hadith 99
← Previous Hadith "Allah's Messenger, Abu Bakr, Umar and Uthman opened the Salat with (Al-Hamdu-lillahi rabbil-alamin)."

Jami` at-Tirmidhi Book 2, Hadith 98 Next Hadith → "I heard the Prophet recite: (Not (the way) of those who earned Your anger, nor those who went astray) and he said: 'Amin.' And he stretched it out with his voice."

Jami` at-Tirmidhi Book 2, Hadith 100