I asked Anas bin Malik about the qunut.He replied, "The qunut was performed."I asked, "Before the ruku or after it?"He answered, "Before it."I said, "But so-and-so told me that you said it was after the ruku."He said, "He has lied. The Messenger of Allah ﷺ only performed qunut after the ruku for one month. I believe he had sent a group of men called the Qurra, around seventy in number, to a tribe of polytheists. There was a treaty between those polytheists and the Messenger of Allah ﷺ, but a different group attacked and killed the Qurra. So the Messenger of Allah ﷺ performed qunut for a month, supplicating against them."
سألت أنس بن مالك عن القنوت، فقال: قد كان القنوت. قلت: قبل الركوع أو بعده، قال: قبله. قال: فإن فلانا أخبرني عنك قلت: بعد الركوع، فقال: كذب، إنما قنت رسول الله ﷺ بعد الركوع شهرا، أراه بعث قوما يقال لهم: القراء زهاء سبعين رجلا إلى قوم من المشركين دون أولئك. وكان بينهم وبين رسول الله ﷺ عهد: فقنت رسول الله ﷺ شهرا يدعو عليهم.
Bukhari narrated it in the chapter on Witr (1002), and Muslim in the chapter on mosques (301/677), both of them through Asim, with this wording, and the wording given is Bukhari's. His saying "kadhaba" means "he erred."