question #1 Sahih al-Bukhari 4977, Book 65, Hadith 499 : What is the significance of accepting the Prophet’s recitation as part of the Qur’an?

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 Messenger (ﷺ) 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 Messenger (ﷺ) has said.”