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 ‏‏

Abu Salama b. 'Abd al-Rahman is reported to have said that he had heard Abu Huraira saying:

I would say prayer along with you which is near to the prayer of the Messenger of Allah (ﷺ). and Abu Huraira recited Qunut in the noon and in the 'Isya' and in the morning prayer, and invoked blessing (of Allah) upon Muslims-and curse upon the unbelievers.
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا مُعَاذُ بْنُ هِشَامٍ، حَدَّثَنِي أَبِي، عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ، قَالَ حَدَّثَنَا أَبُو سَلَمَةَ بْنُ عَبْدِ الرَّحْمَنِ، أَنَّهُ سَمِعَ أَبَا هُرَيْرَةَ، يَقُولُ وَاللَّهِ لأُقَرِّبَنَّ بِكُمْ صَلاَةَ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏ فَكَانَ أَبُو هُرَيْرَةَ يَقْنُتُ فِي الظُّهْرِ وَالْعِشَاءِ الآخِرَةِ وَصَلاَةِ الصُّبْحِ وَيَدْعُو لِلْمُؤْمِنِينَ وَيَلْعَنُ الْكُفَّارَ ‏.‏
Reference : Sahih Muslim 676
In-book reference : Book 5, Hadith 380
USC-MSA web (English) reference : Book 4, Hadith 1432
  (deprecated numbering scheme)