I asked Anas, may Allah be pleased with him, about the qunut. He replied, "It is before the bowing."I said, "But so-and-so claims that you said it is after the bowing."He said, "He has lied."Then he narrated to us from the Prophet ﷺ that he performed the qunut for a month after the bowing, supplicating against some clans of Banu Sulaym. He said, "The Prophet ﷺ sent forty," or "seventy," the narrator was uncertain, "of the reciters to a group of the polytheists. These people intercepted them and killed them, even though there was a covenant between them and the Prophet ﷺ. I never saw him grieve over anyone as deeply as he grieved over them."
سألت أنسارضي ٱلله عنه عن القنوت قال: قبل الركوع فقلت: إن فلانا يزعم أنك قلت بعد الركوع. فقال: كذب، ثم حدثنا عن النبي ﷺ أنه قنت شهرا بعد الركوع، يدعو على أحياء من بني سليم، قال: بعث أربعين- أو سبعين يشك فيه- من القراء إلى أناس من المشركين، فعرض لهم هؤلاء، فقتلوهم، وكان بينهم وبين النبي ﷺ عهد، فما رأيته وجد على أحد ما وجد عليهم.
Bukhari narrated it in the Book of Jizya and Truces (3170), and Muslim in the Book of Mosques and Places of Prayer (677:302), both of them via Asim, with the same chain. The wording given is Bukhari's, and Muslim abridged it.