The Prophet ﷺ would not perform qunut except when he was praying for someone or praying against someone. When he said, "Allah hears the one who praises Him," he would say, "Our Lord, to You belongs all praise. O Allah, save..." and the rest of the hadith was mentioned.
أن النبي ﷺ كان لا يقنت إلا أن يدعو لأحد، أو يدعو على أحد، وكان إذا قال: سمع الله لمن حمده قال: ربنا ولك الحمد اللهم انج فذكر الحديث.
Ibn Khuzayma (619) narrated it from Muhammad bin Yahya, who said, Abu Dawud narrated to us, who said, Ibrahim bin Saad narrated to us, from Zuhri, from Saeed and Abu Salama, from Abu Hurairah, and he related it.Its origin is in Sahih Bukhari (4560), from Musa bin Ismail, who said, Ibrahim bin Saad narrated to us with his chain of transmission, and he related it as mentioned above.Ibn Jawzi attributed it in Tahqiq (2/431) to Ibn Hibban (though I did not find it in the printed copies), and the author of Tanqih said, "Its narrators are reliable."Ibn Hajar said in Diraya (1/195), commenting on it, "Ibn Khuzayma has something similar, and the chain of transmission of each of them is sahih."