Mishkat al-Masabih 20 Game and Animals Which May Be Slaughtered كتاب الصيد والذبائح 74

وَعَنْ أَبِي هُرَيْرَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَا سَالَمْنَاهُمْ مُنْذُ حَارَبْنَاهُمْ وَمَنْ تَرَكَ شَيْئًا مِنْهُمْ خِيفَةً فَلَيْسَ منَّا» . رَوَاهُ أَبُو دَاوُد

Abu Huraira reported God’s messenger as saying, “We have not made peace with them 1 since we fought with them, so he who leaves any of them alone through fear does not belong to us.” 1. i.e. snakes. Abu Dawud transmitted it.