Conquest of Mecca
In 628 AD, Ali was instructed to write down the Treaty of Hudaybiyyah, the peace treaty between Muhammad and the Quraysh. In 630 AD, the year before the Conquest of Mecca, when Abu Bakr was leading the Hajj, Muhammad recited Surah Bara'ah Min al-Mushrikin (declaring that Muhammad and the Islamic community no longer bound by agreements made earlier with Arab polytheists.) by Ali to the people of Mecca. One year later, in 631, Ali was sent to Yemen to spread the teachings of Islam there which is known as Expedition of Ali ibn Abi Talib.