Narrated 'Abdur-Rahman bin Abu Nu'm:
that a man from the people of Al-'Iraq asked Ibn 'Umar about the blood of a gnat that gets on the clothes. Ibn 'Umar said "Look at this one, he asks about the blood of a gnat while they killed the son of the Messenger of Allah (ﷺ)! And I heard the Messenger of Allah (ﷺ) said: 'Indeed Al-Hasan and Al-Husain - they are my two sweet basils in the world.'" (IT)
English reference (IT): Vol. 1, Book 46, Hadith 3770 (IT)
Arabic reference (IT): Book 49, Hadith 4139 (IT)