Flag Of Prophet Muhammad

The early Muslim community did not really have a symbol. During the time of the Islamic prophet, Muhammad, Muslim armies and caravans flew simple solid-coloured flags (generally black or white) for identification purposes. In later generations, the Muslim leaders continued to use a simple black, white, or green flag with no markings, writings, or symbolism on it.

Muhammad used flags of different colours in different Ghazwat (or campaigns commanded by Muhammad himself) and Saraya (or campaigns commanded by any Sahaba (the companions of Muhammad)). The major flag of Muhammad was known as Al-Uqaab, it was pure black, without symbols or markings.[2] Its name and colour was derived from the flag of the Quraysh, an Arabian tribe, whose flag, also called Al-Uqaab, was black with an eagle.[3]

Al-Rashida
All four Rashida Caliphs and Hasan followed the path of the Prophet and did not symbolize Islam with a standard. However, Uqaab - the black flag continued to be used in campaigns and also as the national flag of newly born Islamic Empire.