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: “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.” Authentic hadith - Narrated by Muslim