Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: Some companions of the Prophet (peace and blessings of Allah be upon him) were shown Laylat al-Qadr in the last seven nights (in their dreams), so the Prophet (peace and blessings of Allah be upon him) said: I have noticed that your dreams agree regarding the last seven nights, so whoever wants to search for it should search for it in the last seven nights.
Hadith Referenceصحیح ابن حبان / كتاب الصوم / 3675
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «صحيح أبي داود» (1253): ق.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط الشيخين