Mukhtasar Bukhari

Narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that some of the companions of the Prophet (peace and blessings of Allah be upon him) were shown in their dreams that Laylat al-Qadr is in the last seven nights of Ramadan. So the Messenger of Allah (peace and blessings of Allah be upon him) said: "I see that your dreams have agreed upon the last seven nights, so whoever is seeking Laylat al-Qadr should search for it in the last seven nights."