Sahih al-Bukhari 4089
Sahih al-Bukhari · Book 64: Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) · The Ghazwa of Ar-Raji’, Ri’l, Dhakwan and Bi’r Ma’una and the narration about Khubaib and his companions
Narrated Anas:
حَدَّثَنَا مُسْلِمٌ ، حَدَّثَنَا هِشَامٌ ، حَدَّثَنَا قَتَادَةُ ، عَنْ أَنَسٍ ، قَالَ قَنَتَ رَسُولُ اللَّهِ صلى الله عليه وسلم شَهْرًا بَعْدَ الرُّكُوعِ يَدْعُو عَلَى أَحْيَاءٍ مِنَ الْعَرَبِ.
Allah's Messenger (ﷺ) said Al-Qunut for one month after the posture of Bowing, invoking evil upon some 'Arab tribes.