Entitlement to spoils when an enemy is killed during retreat or general rout.
General Chapter
Al-Mughni
Book of Jihad
Primary text
If the entire enemy force has routed, and a Muslim catches up to a fleeing enemy and kills him, the killer receives no spoils because the condition of exposing oneself to danger in the killing is absent, as the enemy has already neutralized his threat to the Muslims. However, if the enemy flees while active fighting is ongoing (where war involves ebb and flow, 'farru wa karr'), and a Muslim kills him, the spoils belong to the killer. This is supported by the precedent of Salama ibn al-Akwa', whom the Prophet (PBUH) awarded the entire spoils of the enemy he killed while the enemy was fleeing during active engagement.
Supporting text
Scholars such as Abu Thawr, Dawud, and Ibn al-Mundhir hold that the spoils should go to every killer based on the generality of the Hadith regarding spoils and the precedent of Salama. However, the established position argues that the fleeing enemy during an ongoing battle is still considered as 'mutahayyizun ila fi'ah' (aligned with a group) or returning to fight, thus resembling a combatant during the ebb and flow of battle. Conversely, if the enemy rout is final, the threat is neutralized, and the killer did not expose himself to danger, making the ruling similar to that of a captive.