Sahih Bukhari Volume 008, Book 073, Hadith Number 075.

Narated 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 maybe it was better for you. So look for it in the ninth, the seventh, or the fifth (of the last ten days of Ramadan)."