Sunan an-Nasa'i 1179

Qutaybah ibn Sa‘id reported to us, saying: Abu ‘Awanah reported to us, from ‘Abd al-Rahman ibn al-Asamm, who said: Anas ibn Malik was asked about the takbir in prayer. He said: “One says the takbir when bowing, when prostrating, when raising one’s head from prostration, and when standing up after the two rak‘ahs.” Hutaym asked, “From whom did you learn this?” He replied, “From the Prophet (ﷺ), Abu Bakr, and ‘Umar (may Allah be pleased with them).” Then he fell silent. Hutaym asked him, “And ‘Uthman?” He replied, “And ‘Uthman.”