How can the اختلاف (disagreement) among the Salaf be justified regarding whether the Basmalah is an ayah of Surat Al-Fatihah or not, even though the Qur’an was transmitted by Tawatur?

Muslims are in agreement that Allah Almighty has preserved the Holy Quran from addition and omission, in fulfillment of His saying: (Indeed, it is We who sent down the Dhikr (the Qur’an), and indeed, We will be its guardian) [Al-Hijr: 9]. They considered anyone who claims there is an addition or omission in it to be a disbeliever.

However, the disagreement among scholars regarding whether the Basmala is a verse of the Quran does not fall within this consensus, as the Ummah has agreed not to declare a disbeliever anyone who affirms or denies it, due to the scholarly disagreement on the matter. It has been mentioned that the Basmala is a verse in Surat An-Naml by consensus, while it is not a verse in Surat Bara'ah by consensus. Opinions varied concerning other surahs: some said it is not a verse at all, others said it is a verse only in Al-Fatihah, and some said it is a verse at the beginning of every surah.

These opinions have been reconciled by stating that the Basmala is a verse in some recitations but not others, similar to the variations in words and letters in other recitations; what is established in one recitation may not be established in another.