Sahih Bukhari

Narrated Ibn Abi Na'm:I was present when a man asked Ibn `Umar about the blood of mosquitoes. Ibn `Umar said, ""From where are you?"" The man replied. ""From Iraq."" Ibn `Umar said, ""Look at that! he is asking me about the blood of Mosquitoes while they (the Iraqis ) have killed the (grand) son of the Prophet. I have heard the Prophet (ﷺ) saying, ""They (Hasan and Husain) are my two sweet-smelling flowers in this world