
From the life of Hazrat Ali (ra) bin Abi Talib
What services did Hazrat Ali (ra) render during the era of the three Khalifas before him? After the demise of the Holy Prophet (sa), many of the Arab tribes became apostates and the hypocrites of Medina also began to grow bold in their opposition. Many people from among the Banu Hanifah and Yamamah joined with Musaylimah Kazzab, whilst many others from among the Banu Asad, Tayy and various other tribes joined with Tulaiha Asadi. Just like Musaylimah Kazzab , Tulaiha Asadi also declared to be a prophet. Disorder became widespread and the situation became increasingly grave. In such circumstances, Hazrat Abu Bakr (ra) sent an army under the command of Hazrat Usama (ra) and thus very few people were left behind with him. Subsequently, many of the Bedouins thought of capturing Medina and began to plot an attack. Hazrat Abu Bakr (ra) appointed guards at the various entrances into Medina, who along with their men, would guard Medina at night. Amongst those who were assigned to oversee these guards was Hazrat Ali (ra) bin Abi Talib, Zubair (ra) bin al-Awam, Talhara bin Abdillah, Saad (ra) bin Abi Waqas, Abdur Rahman (ra) bin Auf and Abdullah (ra) bin Mas‘ud.
(Ibn Kathir, Al-Bidayah wa al-Nihayah, Vol. 7 [Beirut, Lebanon: Dar al-Kutub al-Ilmiyyah, 2001] 307-308)
Thus, even during this time, Hazrat Ali (ra) was appointed to oversee this section of the army which was assigned to guard Medina.