The prayer of the one who did not recite the Opening of the Book (Surat al-Fātihah) is invalid Perhaps you recite behind your Imām? We said: Yes, that is so, O Messenger of Allah. He said: Do not do so except with Sūrat al-Fātihah, since the prayer is invalid for the one who does not recite it The worst of thieves among people is the one who steals his prayer." He said: "How does he steal his prayer?" He said: "He does not perform its Rukū‘ or prostration perfectly