Sahih al-Bukhari 49
Sahih Book of Belief · Hadith 49 of 7,563أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ جَعْفَرٍ، عَنْ حُمَيْدٍ، عَنْ أَنَسٍ، قَالَ أَخْبَرَنِي عُبَادَةُ بْنُ الصَّامِتِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم خَرَجَ يُخْبِرُ بِلَيْلَةِ الْقَدْرِ، فَتَلاَحَى رَجُلاَنِ مِنَ الْمُسْلِمِينَ فَقَالَ " إِنِّي خَرَجْتُ لأُخْبِرَكُمْ بِلَيْلَةِ الْقَدْرِ، وَإِنَّهُ تَلاَحَى فُلاَنٌ وَفُلاَنٌ فَرُفِعَتْ وَعَسَى أَنْ يَكُونَ خَيْرًا لَكُمُ الْتَمِسُوهَا فِي السَّبْعِ وَالتِّسْعِ وَالْخَمْسِ ".
Narrated by Ubada bin As-Samit
"Allah's Messenger (ﷺ) went out to inform the people about the (date of the) night of decree (Al-Qadr) but there happened a quarrel between two Muslim men. The Prophet (ﷺ) said, "I came out to inform you about (the date of) the night of Al-Qadr, but as so and so and so and so quarrelled, its knowledge was taken away (I forgot it) and maybe it was better for you. Now look for it in the 7th, the 9th and the 5th (of the last 10 nights of the month of Ramadan)
References
Sahih al-Bukhari 49
In-book: Book 2, Hadith 42 Source: hadith-api (fawazahmed0)