Hadithcore
Mishkat al-Masabih, 3952

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

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

References1 variant
In-Book Reference
Book 19, Hadith 164