That the Messenger of Allah ﷺ said: "Kill the elder men among the idolaters and spare the Sharkh amont them." And the Sharkh are the boys who did not begin to grow pubic hair.
أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ اقْتُلُوا شُيُوخَ الْمُشْرِكِينَ وَاسْتَحْيُوا شَرْخَهُمْ وَالشَّرْخُ الْغِلْمَانُ الَّذِينَ لَمْ يُنْبِتُوا