Asim reported:

I asked Anas whether Qunut was observed (by the Holy prophet) before ruku' or after ruku'. He replied: Before ruku'. I said: People conceive that the Messenger of Allah (ﷺ) observed Qunut after the ruku'. He said: The Messenger of Allah (ﷺ) observed Qunut (after the ruku' as the people conceive it) for a mouth invoking curse upon those persons who had killed men among his Companions who were called the reciter (of the Qur'an).

وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ قَالاَ حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنْ عَاصِمٍ، عَنْ أَنَسٍ، قَالَ سَأَلْتُهُ عَنِ الْقُنُوتِ، قَبْلَ الرُّكُوعِ أَوْ بَعْدَ الرُّكُوعِ فَقَالَ قَبْلَ الرُّكُوعِ ‏.‏ قَالَ قُلْتُ فَإِنَّ نَاسًا يَزْعُمُونَ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَنَتَ بَعْدَ الرُّكُوعِ ‏.‏ فَقَالَ إِنَّمَا قَنَتَ رَسُولُ اللَّهِ صلى الله عليه وسلم شَهْرًا يَدْعُو عَلَى أُنَاسٍ قَتَلُوا أُنَاسًا مِنْ أَصْحَابِهِ يُقَالُ لَهُمُ الْقُرَّاءُ ‏.‏