21. And (there are) other (great victories) yet beyond your reach. Allah has encompassed them (for you in the future).* And Allah is All-Capable of everything.
* These include the Conquests of Mecca, Hawazin, Hunayn, and then, the Conquests of Persia and Byzantine. Before the Treaty of al-Hudaybiya, the Muslims could not campaign to the north of Medina due to the threat from the south. But now that a truce was signed with the Quraysh and their allies, they could freely deal with the threat from the north. The Muslims were able to concentrate their energy against Khaybar as they had freed themselves from the attacks of their southern enemies, the Quraysh until the Quraysh themselves broke the Treaty. Breaking the Treaty was a significant political development, marking a turning point for the Muslims. That is why the Qur’an miraculously declared the Treaty of al-Hudaybiya a ‘clear victory’ as it opened the doors to great historical conquests. It led to the Conquests of Khaybar, Mecca and the entire Arabian Peninsula, and later, the expansion of the Islamic state outside of Arabia, overtaking both the Persian and Byzantine empires.
