It is narrated from Sayyiduna Samurah bin Jundub (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: Kill the brave and strong men of the polytheists who fight, and leave the minor children. Abdullah (may Allah have mercy on him) says: I asked my father, Imam Ahmad (may Allah have mercy on him), about the explanation of the hadith "Kill the elders of the polytheists," and he said: The issue with the elder is that it is unlikely that he will become a Muslim, whereas the boy is closer to accepting Islam than the elder. By "al-sharh" is meant the boys.
Hadith Referenceالفتح الربانی / كتاب الجهاد / 5000
Hadith Gradingمحدثین:ضعیف
Hadith Takhrij«اسناده ضعيف، أخرجه ابوداود: 2670، والترمذي: 1583، (انظر مسند أحمد ترقيم الرسالة: 20145 ترقیم بيت الأفكار الدولية: 20407»
Brief Explanation
Benefits: … In this hadith, "shuyukh" refers to those people who have reached the age of forty years, that is, strong, battle-ready men. It does not refer to those elderly old men in whom strength and sound judgment have ceased.