Sahih Bukhari Volume 8, Book 78, Hadith 5996

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا مَهْدِيٌّ، حَدَّثَنَا ابْنُ أَبِي يَعْقُوبَ، عَنِ ابْنِ أَبِي نُعْمٍ، قَالَ كُنْتُ شَاهِدًا لاِبْنِ عُمَرَ وَسَأَلَهُ رَجُلٌ عَنْ دَمِ الْبَعُوضِ‏.‏ فَقَالَ مِمَّنْ أَنْتَ فَقَالَ مِنْ أَهْلِ الْعِرَاقِ‏.‏ قَالَ انْظُرُوا إِلَى هَذَا، يَسْأَلُنِي عَنْ دَمِ الْبَعُوضِ وَقَدْ قَتَلُوا ابْنَ النَّبِيِّ صلى الله عليه وسلم وَسَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَقُولُ ‏"‏ هُمَا رَيْحَانَتَاىَ مِنَ الدُّنْيَا ‏"‏‏.‏

Narrated By 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 saying, "They (Hasan and Husain) are my two sweet-smelling flowers in this world."