Nasai

This pertains to the conquest of Makkah; therefore, a flag was necessary. Otherwise, on the occasion of the Farewell Pilgrimage (Hajjat al-Wada‘), there was no flag or the like. In some narrations, it is mentioned that the flag of the Prophet (sallallahu alayhi wa sallam) was black. There is no contradiction in this. The main flag of the army was black, and the personal flag of the Prophet (sallallahu alayhi wa sallam) was white. In any case, there are several flags in war. Even during the conquest of Makkah, the Muhajirun had a separate flag, the Ansar had a separate one, and likewise for other groups.