Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1937
'Utba reported that his father Waqid al-Laithi said: 'Umar b. Khattab asked me what the Messenger of Allah (may peace be upon him) recited on 'Id day. I said:" The Hour drew near" and Qaf. By the Glorious Qur'an".