In Shawwāl of 5/February 627, during the Battle of Confederates (al-Aḥzāb) or Battle of the Trench (al-Khandaq), Ali (a) once again held the position of being the flag-bearer of the Islamic army, as he had done in most of the previous battles.3 After digging a ditch at the suggestion of Salmān al-Fārsī, Ali (a) and a group of the Companions took charge of protecting the passages of the ditch to prevent the Meccan army from crossing.4 When ʿAmr b. ʿAbd Wadd managed to cross the trench, he boldly issued a challenge to the Muslim warriors by reciting three paeans. However, among the Muslim ranks, it was only Ali (a) who fearlessly stepped forward. On the third occasion when Ibn ʿAbd Wadd issued a challenge to the companions, the Prophet (s) declared, “Whoever engages in combat with ʿAmr, I guarantee Paradise for him on behalf of Allah.” However, despite the Prophet’s assurance, none of the companions stepped forward except for Ali ibn Abi Talib(a).

 The Prophet (s) entrusted his own sword to Ali (a), placed his own turban upon Ali’s head, offered a prayer for his success, and then dispatched him to confront ʿAmr in battle. As Ali (a) prepared to enter the battlefield, the Prophet (s) beseeched Allah in prayer, saying, “O Allah! Grant Ali Your assistance against him.” On another account, as Ali (a) was heading towards the battlefield, the Prophet (s) declared, “The entirety of faith confronts the entirety of polytheism in this battle.”

On foot, Ali (a) approached the battlefield and presented ʿAmr with three options: to embrace Islam, engage in combat, or return to his homeland. Enraged by these words, ʿAmr dismounted from his horse and engaged in a fierce battle with Ali (a), ultimately resulting in his own death. In a particular account, when ʿAmr b. ʿAbd Wadd was on the verge of defeat, Ali (a) momentarily paused the fight, hesitating to deliver the final blow. The Muslim soldiers observing the scene from a distance were puzzled by this pause, and some of them voiced their objections and concerns. After Amīr al-Muʾminīn Ali (a) finally emerged victorious over ʿAmr, the Prophet (s) inquired about the reason for his momentary pause before delivering the final blow. In response, Ali (a) explained, “He [ʿAmr b. Abd Wadd] cursed my mother and spat on my face. I was concerned that I would defeat him out of personal anger. Therefore, I waited for a brief moment and then vanquished him, solely for the sake of Allah.” Regarding Ali (a)’s encounter with ʿAmr b. ʿAbd Wadd, the Prophet (s) remarked, “The battle of Ali ibn Abi Talib(a) against ʿAmr b. ʿAbd Wadd on the day of the trench surpasses the collective deeds of my followers until the Day of Resurrection.” Furthermore, in another hadith, the Prophet (s) stated, “Any single strike delivered by Ali on the day of the trench surpasses the collective acts of worship performed by both humans and jinn.”

 Upon the Prophet’s return from the Battle of Confederates on Dhū l-Qaʿda 23rd, 5/April 15, 627, he issued a command for the Muslims to proceed towards the forts of the Banū Qurayẓa, a Jewish tribe, in order to exert control over them. Initially, the Prophet (s) dispatched Ali (a) and a group of 30 individuals from the Khazraj tribe to the forts of the Banū Qurayẓa in order to assess the tribe’s readiness for war. As Ali ibn Abi Talib(a) positioned his flag near the forts of the Banū Qurayẓa, the Jewish inhabitants responded by directing curses towards the Prophet (s) and his wives. Furthermore, there are reports that when the Banū Qurayẓa Jews caught sight of Ali (a), they exclaimed in fear, saying, “The killer of ʿAmr [b. ʿAbd Wadd] has come to us.” During the course of the battle, the fort of the Banū Qurayẓa proved to be unconquerable until one day when Ali (a) made a solemn oath, vowing to capture the fort or meet a martyrdom similar to that of Ḥamza b. ʿAbd al-Muṭṭalib. Faced with this formidable determination, the Jews became apprehensive and sent a representative to the Prophet (s), seeking a guarantee of safety for their tribe.