Shi'ih - Sunni

In the Tablet of Salman Bahá'u'lláh explains that in the Islamic Dispensation the letter of negation stood above that of affirmation. Those among the followers of Muhammad who disregarded His wishes about the appointment of His successor and violated His wishes after His passing, dominated over the faithful ones and ruled over them for centuries.

https://bahai-library.com/rev_bahaullah_4/taherzadeh_revelation_bahaullah_4.txt