Mishkat al-Masabih 19 Jihad كتاب الجهاد 164

وَعَن سَمُرَة بن جُنْدُبٍ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «اقْتُلُوا شُيُوخَ الْمُشْرِكِينَ وَاسْتَحْيُوا شَرْخَهُمْ» أَيْ صِبْيَانَهُمْ. رَوَاهُ التِّرْمِذِيّ وَأَبُو دَاوُد

Samura b. Jundub reported the Prophet as saying, “Kill the old men who are polytheists, but spare their sharkh i.e., their children. Tirmidhi and Abu Dawud transmitted it.