Single combat is permissible subject to two conditions. The first is that the person possess courage and valor, and know himself capable of withstanding an opponent. If he lacks this ability, he must be prohibited from engaging in it. The second is that he not be the army’s commander, whose loss would affect the army. For the loss of a capable commander leads to defeat. The Messenger of Allah (peace and blessings be upon him) engaged in single combat only out of confidence in Allah Most High’s promise of victory and its fulfillment; this is not the case for anyone else.

When exhorting the army to jihad, it is permissible for its commander to expose to martyrdom one of those eager for it whom he knows would, if killed in battle, produce one of two effects: either inspiring the Muslims to fight out of zeal for his sake, or demoralizing the polytheists by boldly confronting them in support of the religion. It has been related from Muḥammad ibn Isḥāq that the Messenger of Allah (peace and blessings be upon him) emerged from the shelter on the day of Badr and exhorted the people to jihad, saying: “By Him in Whose Hand is my soul, no man will fight them today and be killed seeking Allah’s reward, advancing and not retreating, except that Allah will admit him to Paradise.”

It is not permissible to kill women or children in war or otherwise, unless they fight, because the Prophet (peace and blessings be upon him) prohibited killing them. If the enemy uses their women and children as shields in battle, and it is impossible to engage the enemy without killing the women and children, then it is permissible to kill the enemy; however, the women and children must not be deliberately targeted. The same applies if they use Muslim captives as shields, and it is impossible to kill the enemy without killing the captives. Abū Bakr mentioned this in his Kitāb al-Khilāf (Book of Legal Disagreement). Aḥmad also indicated this in the narration of Bakr ibn Muḥammad: “Regarding a group that is besieged and protects itself with Muslim children, setting them in front of itself: I would prefer that they not be attacked, unless there is fear that the besieged forces will emerge against them and leaving them unharmed would harm the Muslims; in that case, they may shoot at them.”

It is permissible to hamstring the enemy’s horses beneath them when they fight upon them. Ḥanẓalah ibn Abī ʿĀmir hamstrung the horse of Abū Sufyān ibn Ḥarb on the day of Uḥud and mounted him in order to kill him, whereupon Ibn Shuʿūb saw him and rushed toward Ḥanẓalah. No Muslim may hamstring his own horse, since it is a source of strength that Allah Most High has commanded Muslims to prepare for fighting His enemy: “And prepare against them whatever you are able of power and steeds of war by which you terrify the enemy of Allah and your enemy” (Quran 8:60).

It has been related that Jaʿfar ibn Abī Ṭālib charged into battle on the day of Muʾtah on a light-colored horse of his. When the fighting became intense, he dismounted and hamstrung it. It is possible that he did this so that the polytheists would not use it to gain strength against the Muslims.