“To cut off a flank from those who disbelieved or to restrain them, thus they turned back disappointedly”.
If the enemies of believers were three thousand in number, the Lord had promised the believers to empower them by sending down three thousand Angels. Not only that, if the believers are heedful and are giving preference to the Hereafter than worldly life, Lord will strengthen them with specially marked Angels from the sudden attack of the enemy. All these promises were given to them as a herald and for peace and tranquility of hearts. The Three-Time-Knower Lord can avoid battle and lead the believers into victory without any suffering. The Battle of Badr was happened to reveal on which side the Truth exists. But the Battle of Uhud was happened to distinguish the believers and hypocrites among the followers of Messenger as explained in verses 3: 166-167. In the Battle of Uhud, the disbelievers who came from Mecca turned back themselves disappointedly without any gain. That is why it is told in verse “To cut off a flank from those who disbelieved”. The Impartial Lord will not punish those who have not received the Book but will punish the hypocrites and their blind followers since they hide and reject Adhikr which is the Food, Cloth, and Sight of the human soul. See explanation 2: 154-157, 213-214, and 9: 73.