Sahih Bukhari Volume 8, Book 78, Hadith 6051

حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا بِشْرُ بْنُ الْمُفَضَّلِ، عَنْ حُمَيْدٍ، قَالَ قَالَ أَنَسٌ حَدَّثَنِي عُبَادَةُ بْنُ الصَّامِتِ، قَالَ خَرَجَ رَسُولُ اللَّهِ صلى الله عليه وسلم لِيُخْبِرَ النَّاسَ بِلَيْلَةِ الْقَدْرِ، فَتَلاَحَى رَجُلاَنِ مِنَ الْمُسْلِمِينَ، قَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ خَرَجْتُ لأُخْبِرَكُمْ، فَتَلاَحَى فُلاَنٌ وَفُلاَنٌ وَإِنَّهَا رُفِعَتْ، وَعَسَى أَنْ يَكُونَ خَيْرًا لَكُمْ، فَالْتَمِسُوهَا فِي التَّاسِعَةِ وَالسَّابِعَةِ وَالْخَامِسَةِ ‏"‏‏

Narrated By 'Ubada bin As-Samit : Allah's Apostle went out to inform the people about the (date of the Night of decree (Al-Qadr). There happened a quarrel between two Muslim men. The Prophet said, "I came out to inform you about the Night of Al-Qadr, but as so-and-so and so-and-so quarrelled, so the news about it had been taken away; and may be it was better for you. So look for it in the ninth, the seventh, or the fifth (of the last ten days of Ramadan)."