Abdullah bin Umar was asked about a person in the state of ihram. Shuba said, I think the question was, "Does he kill flies?"He replied, "The people of Iraq ask about flies, yet they killed the grandson of the Messenger of Allah ﷺ. The Prophet ﷺ said, 'They are my two sweet basils from this world.'"
عن عبد الله بن عمر- وسأله عن المحرم، قال شعبة: احسبه، يقتل الذباب؟- فقال: اهل العراق يسألون عن الذباب وقد قتلوا ابن ابنة رسول الله ﷺ، وقال النبي ﷺ: هما ريحانتاي من الدنيا.
Bukhari narrated it in the Virtues of the Companions (3753) from Muhammad bin Bashshar, who said, we were told by Ghundar, who said, we were told by Shubah, from Muhammad bin Abu Yaqub, I heard Ibn Abu Nuaym, I heard Abdullah bin Umar, and he related it.In another wording, "Ibn Abu Nuaym said, I was present with Ibn Umar when a man asked him about the blood of a mosquito. He said, 'Where are you from?' The man said, 'From the people of Iraq.' He said, 'Look at this man asking me about the blood of a mosquito, when they have killed the son of the Prophet ﷺ...'"Bukhari narrated it in the Book of Manners (5994) from Musa bin Ismail, who said, we were told by Mahdi, who said, we were told by Ibn Abu Yaqub, with the same chain.