Book of Jihād
Jihād is a communal obligation (farḍ kifāyah); it becomes individually binding when one is actually present in battle, when his town is besieged, or when a person vested with authority summons him to march (1). Guarding the frontier (ribāṭ) is recommended (2), and its full term is forty days. Anyone whose parents are both Muslims may not volunteer for jihād without their permission.
The commander inspects his army at the time of departure, excluding anyone who spreads defeatism, alarm, or the like (3). The troops are required to obey him and remain steadfast with him, and it is not permissible to set out on a campaign without his leave—unless an enemy takes them by surprise and they fear his onslaught (4).
Spoils of War (Ghanīmah), Fayʾ, and Their Rulings
Booty becomes owned as soon as it is seized, even while still in enemy territory. It belongs to all combatants who were present at the engagement and is first subjected to the one-fifth division (khums) (5). That fifth is allocated as follows: one share for public interests, one for the Prophet’s relatives, one for orphans, one for the poor, and one for wayfarers. The remainder of the booty is then distributed among the main army and its detachments after any discretionary rewards (nafl) have been set aside: the foot-soldier receives one share, and the cavalryman receives three.