Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 75
Narrated '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)."