Hazrat Sha'bi (may Allah have mercy on him) said: A Muslim prisoner who is in the custody of the enemy—if he remains firm on his religion—then he becomes an heir and inheritance can also be taken from him.
Hadith Referenceسنن سعید بن منصور / كتاب الجهاد / 4006
Hazrat Shurayh (may Allah have mercy on him) said: A prisoner becomes an heir. Because he is in the possession of the enemy and is most in need of his share. Ransom should be given for him or his share should be set aside.
Hadith Referenceسنن سعید بن منصور / كتاب الجهاد / 4007
Hadith Takhrij«أخرجه الدارمي فى «مسنده» برقم: 3134، وسعيد بن منصور فى «سننه» ترقيم الدرالسلفية برقم:، 2831، وعبد الرزاق فى «مصنفه» برقم: 19202، وابن أبى شيبة فى «مصنفه» برقم: 32123، 33502»