Sahih al-Bukhari, Book 78, Hadith 25 (In-Book) ⓘ

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

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 ‏" ‏‏.‏