Surrender&Die

A. Prisoners of war, in the sense of the present Convention, are persons belonging to one of the following categories, who have fallen into the power of the enemy: (1) Members of the armed forces of a Party to the conflict, as well as members of militias or volunteer corps forming part of such armed forces. (2) Members of other militias and members of other volunteer corps, including
those of organized resistance movements, belonging to a Party to the conflict and operating in or outside their own territory, even if this territory is occupied, provided that such militias or volunteer corps, including such organized resistance movements, fulfil the following conditions: (a) that of being commanded by a person responsible for his subordinates; (b) that of having a fixed distinctive sign recognizable at a distance; (c) that of carrying arms
openly; (d) that of conducting their operations in accordance with the laws and customs of war.
Geneva Convention

(c) To kill or wound an enemy who, having laid down his arms, or having no longer means of defence, has surrendered at discretion;
The Hague Regulations 


O Prophet! Say to those who are captives in your hands: ‘If Allah finds any good in your hearts, He will give you something better than what has been taken from you and He will forgive you. For Allah is Oft Forgiving, Most Merciful.” Surah Anfal

As for fighting the Khawarij, and the Zakat deniers, they are to be fought, until they accept the established laws of the Prophet (sallallaahu alaihi wassalam). And if they have a denying group (who insist on their refusal), there is no doubt that it is permissible to kill their prisoners, to pursue their fugitives and to get rid of their wounded. And if these are in their countries while they are on what they are, the Muslims must go to them to kill them until the whole religion is for Allah alone.  
551/28 Ibn Taymiyyah

Le norme circa il trattamento dei prigionieri di guerra, delineate da Allah l'Onnipotente e Misericordioso attraverso il Corano e il Profeta, pace e benedizioni su di lui, sono in pieno accordo con quelle dei trattati internazionali.
Negli unici casi in cui nel corso della storia islamica, ai prigionieri che avevano deposto le armi non è stata concessa la salvezza, si era in presenza di criminali di guerra che per i loro comportamenti antecedenti alla cattura e in virtù della potenziale pericolosità, non potevano essere risparmiati.
Negli ultimi giorni il comparto media di Hayat Tahrir al Sham ha diffuso varie sequenze di battaglie attorno ad Hama nelle quali in apparenza gli appartenenti a Daesh si erano arresi deponendo le armi in un intervallo di tempo da ritenere ragionevole.
Le istruzioni emanate evidentemente dal consiglio shariatico hanno fatto in modo da rendere necessaria l'esecuzione immediata.
Finchè non rivedrà le proprie posizioni religiose, Daesh è un nemico dell'Islam.
In un contesto di guerra va affrontato come tale.