Sahih Bukhari | Volume 6 | Hadith Number 501

Narrated by Zirr bin Hubaish
I asked Ubai bin Ka'b, "O Abu AlMundhir! Your brother, Ibn Mas'ud said so-and-so (i.e., the two Mu'awwidh-at do not belong to the Qur'an)." Ubai said, "I asked Allah's Apostle about them, and he said, 'They have been revealed to me, and I have recited them (as a part of the Qur'an)," So Ubai added, "So we say as Allah's Apostle has said."

Page 143 of 143