Sahih Muslim Book 4, Hadith Number 785.
Chapter : The reciting of al-Fatiha in every Rakah of prayer is obligatory.
This Hadith has been narrated by Qatada with the same chain of transmitters that the Messenger of Allah (may peace be upon him) observed Zuhr prayer and said: I felt that someone amongst you was disputing with me (in what I was reciting).