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.
Al-'Abbas said, "Messenger of God, we wish to sweep out Zamzam, but in it there are some of these jinnan," meaning small snakes; so God’s messenger ordered that they should be killed.
‘Ikrima told on the authority of Ibn ‘Abbas, saying he was sure that he traced it back to the Prophet, that he used to order snakes to be killed and say, "He who leaves them alone fearing that one will come to take revenge does not belong to us."