Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever kills a snake receives seven good deeds, whoever kills a gecko receives one good deed, and whoever leaves a snake alone out of fear of what its consequence will be is not one of us."
Ahmad, and al-Tabarani in al-Mu'jam al-Kabir, recorded it; the narrators of Ahmad are the narrators of the Sahih, except that the narrator al-Musayyab bin Rafi' did not hear from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him). And Allah knows best.