It was narrated from Anas bin Malik that the Messenger of Allah ﷺ used to recite Qunut in the Subh prayer, and he used to supplicate in it against one of the Arab tribes for a month, then he stopped doing so.
أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يَقْنُتُ فِي صَلاَةِ الصُّبْحِ يَدْعُو عَلَى حَىٍّ مِنْ أَحْيَاءِ الْعَرَبِ شَهْرًا ثُمَّ تَرَكَ