The Messenger of Allah ﷺ sent seventy men, who were known as "the Reciters," on a particular mission. Two clans of Banu Sulaym, Ril and Zakwan, intercepted them at a well called Bir Maunah.The men said, "By Allah, we did not come for you. We are simply passing through on an errand for the Prophet ﷺ."But they killed them. So the Prophet ﷺ invoked Allah against them for a month during the dawn prayer, and that was the beginning of the qunut. Before that, we had not been performing the qunut.
بعث رسول الله ﷺ سبعين رجلا لحاجة يقال لهم: القراء. فعرض لهم حيان من بني سليم- رعل وذكوان- عند بئر يقال له: بئر معونة، فقال القوم: والله ما إياكم أردنا إنما نحن مجتازون في حاجة للنبي ﷺ فقتلوهم. فدعا النبي ﷺ عليهم شهرا في صلاة الغداة وذلك بدء القنوت، وما كنا نقنت.
Bukhari narrated it in the Maghazi chapter (4088) from Abu Muamar, who said, Abdul-Warith told us, Abdul-Aziz told us, from Anas, and he mentioned it.His words "for a need" refer to teaching, as is made explicit in the version narrated by Muslim in the Book of Leadership (677:147), which he narrated from Muhammad bin Hatim, who said, Affan told us, Hammad told us, Thabit informed us, from Anas bin Malik, who said, some people came to the Prophet ﷺ and said, "Send with us some men to teach us the Quran and the sunnah." So he sent to them seventy men from the Ansar, who were called the Qurra (Quran reciters), among them my uncle Haram. They used to recite the Quran and study it together at night, learning. During the day they would bring water and place it in the masjid, and they would gather firewood and sell it, and with the proceeds buy food for the people of the Suffah and for the poor.The Prophet ﷺ sent them out to those people, but the enemy ambushed them and killed them before they reached their destination. They said, "O Allah, convey from us to our Prophet that we have met You, and we are pleased with You and You are pleased with us."He said, and a man came upon Haram, Anas's uncle, from behind and pierced him with a spear until it went right through him. Haram said, "I have triumphed, by the Lord of the Kaaba."Then the Messenger of Allah ﷺ said to his companions, "Your brothers have been killed, and they said, 'O Allah, convey from us to our Prophet that we have met You, and we are pleased with You and You are pleased with us.'"