Asim reported,

I asked Anas رضي الله عنه about the qunut, and he said, "It was before the bowing."I said, "So-and-so claims that you said it was after the bowing."He replied, "He has lied."Then he narrated to us from the Prophet ﷺ that he made qunut for a month after the bowing, supplicating against some clans of Banu Sulaym. He said that the Prophet ﷺ had sent forty, or seventy (the narrator was uncertain), of the reciters of the Quran to a group of polytheists, but these people intercepted them and killed them, even though there was a treaty between them and the Prophet ﷺ. I never saw the Prophet ﷺ grieve over anyone as much as he grieved over them.

Bukhari 3170

Sahih

حدثنا أبو النعمان حدثنا ثابت بن يزيد حدثنا

عاصم قال

سألت أنسا رضي الله 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

البخاري 3170صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Jizya and truce
Chapter
Supplication of the imam against one who broke a covenant
Numbering
Darussalam 3170
Bukhari 3170