Sahih Muslim 2240
Sahih Muslim · Book 39: The Book of Greetings · It Is Recommended To Kill Geckos
وَحَدَّثَنَا مُحَمَّدُ بْنُ الصَّبَّاحِ ، حَدَّثَنَا إِسْمَاعِيلُ يَعْنِي ابْنَ زَكَرِيَّاءَ ، عَنْ سُهَيْلٍ ، حَدَّثَتْنِي أُخْتِي ، عَنْ أَبِي هُرَيْرَةَ ، عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ قَالَ " فِي أَوَّلِ ضَرْبَةٍ سَبْعِينَ حَسَنَةً " .
Abu Huraira reported Allah's Messenger (ﷺ) as saying (that he who kills a gecko) with the first stroke there are seventy rewards for him.