كتاب الْمَسَاجِدِ وَمَوَاضِعِ الصَّلاَةِ
5  
The Book of Mosques and Places of Prayer
(54)
Chapter: It is recommended to say qunut in all prayers if a calamity befalls the Muslims – and refuge is sought from Allah (regarding that). It is recommended to say qunut in Subh at all times. And the clarification that it is to be said after raising the head from bowing in the final rak`ah, and it is recommended to say it out loud
(54)
باب اسْتِحْبَابِ الْقُنُوتِ فِي جَمِيعِ الصَّلاَةِ إِذَا نزَلَتْ بِالْمُسْلِمِينَ نَازِلَةٌ ‏‏
Sahih Muslim 677 b

Muhammad reported:

I asked Anas whether the Messenger of Allah (ﷺ) observed Qunut in the dawn prayer. He said: Yes, (he did so) after the ruku', for a short while.
وَحَدَّثَنِي عَمْرٌو النَّاقِدُ، وَزُهَيْرُ بْنُ حَرْبٍ، قَالاَ حَدَّثَنَا إِسْمَاعِيلُ، عَنْ أَيُّوبَ، عَنْ مُحَمَّدٍ، قَالَ قُلْتُ لأَنَسٍ هَلْ قَنَتَ رَسُولُ اللَّهِ صلى الله عليه وسلم فِي صَلاَةِ الصُّبْحِ قَالَ نَعَمْ بَعْدَ الرُّكُوعِ يَسِيرًا ‏.‏
Reference : Sahih Muslim 677b
In-book reference : Book 5, Hadith 379
USC-MSA web (English) reference : Book 4, Hadith 1434
  (deprecated numbering scheme)