Is it permissible to use the Seal of the Prophet after his death, and what is the ruling on innovating a banner other than the banner of the Eagle (al-Uqāb)? Is it permissible to use the Shahada as a banner for Muslims, knowing that the Messenger’s banner only bore the declaration of Tawhid?

The Prophet, peace and blessings be upon him, did not have a single banner; rather, the banners varied with the changing times. His banner was black and square, made of a fabric called Namira. White, yellow, and red banners were also mentioned. This variation is due to the change in times. It was said that his banner was called "Al-Uqab" (The Eagle) and was black and square, and there was also a white banner. As for writing the declaration of faith, "La ilaha illa Allah, Muhammad Rasul Allah" (There is no god but Allah, Muhammad is the Messenger of Allah), on the banner, it is permissible, even if the hadith stating this is weak. As for differentiating between a banner for peace and a banner for war, there is no evidence for it.