Companions of the Prophet

Bukhari :: Book 5 :: Volume 57 :: Hadith 96

Narrated Ibn Abi Nu'm:

A person asked 'Abdullah bin 'Umar whether a Muslim could kill flies. I heard him saying (in reply). "The people of Iraq are asking about the killing of flies while they themselves murdered the son of the daughter of Allah's Apostle . The Prophet said, They (i.e. Hasan and Husain) are my two sweet basils in this world."