Sahih al-Bukhari 62:98
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 Messenger (ﷺ) . The Prophet (ﷺ) said, They (i.e. Hasan and Husain) are my two sweet basils in this world."
Reference
Sahih al-Bukhari 62:98
In-book reference
Book 62, Hadith 98
Arabic Text
حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا غُنْدَرٌ، حَدَّثَنَا شُعْبَةُ، عَنْ مُحَمَّدِ بْنِ أَبِي يَعْقُوبَ، سَمِعْتُ ابْنَ أَبِي نُعْمٍ، سَمِعْتُ عَبْدَ اللَّهِ بْنَ عُمَرَ، وَسَأَلَهُ، عَنِ الْمُحْرِمِ،، قَالَ شُعْبَةُ أَحْسِبُهُ يَقْتُلُ الذُّبَابَ فَقَالَ أَهْلُ الْعِرَاقِ يَسْأَلُونَ عَنِ الذُّبَابِ وَقَدْ قَتَلُوا ابْنَ ابْنَةِ رَسُولِ اللَّهِ صلى الله عليه وسلم، وَقَالَ النَّبِيُّ صلى الله عليه وسلم " هُمَا رَيْحَانَتَاىَ مِنَ الدُّنْيَا ".