Hadith: If anyone kills a gecko in the first strike will have one hundred good deeds recorded for him; and with the second strike lesser than that and with the third strike lesser than that

عن أبي هريرة رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم : «من قتل وَزَغَةً فِي أَوَّلِ ضَرْبَةٍ فله كذا وكذا حسنة، ومن قتلها في الضَّرْبَةِ الثانية فله كذا وكذا حسنة دون الأولى، وإن قتلها في الضربة الثالثة فله كذا وكذا حسنة». وفي رواية: «من قتل وَزَغًا في أول ضربة كتب له مائة حسنة، وفي الثانية دون ذلك، وفي الثالثة دون ذلك».
[صحيح] - [رواه مسلم]

Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "If anyone kills a gecko with the first strike will have such-and-such reward; and anyone kills it with the second strike will have such-and-such reward, lesser than the first; and anyone kills it with the third strike will have such-and-such reward, lesser than the second.” Another narration reads: "c2">“Anyone kills a gecko with the first strike will have one hundred good deeds recorded for him; and with the second strike lesser than that, and with the third strike lesser than that.”
Sahih/Authentic. - [Muslim]

Explanation

The Prophet (may Allah's peace and blessings be upon him) encourages us to kill geckos. He informs us that anyone kills it with the first blow will have one hundred good deeds written for him; and anyone kills it with the second blow will have less than that (written for him); and whoever kills it with the third blow will have less than that (written for him). The wisdom behind killing geckos is that it was blowing into the fire in which Ibrahīm (peace be upon him) was thrown, and it is harmful and poisonous.