It is narrated from Sayyiduna Ibn Umar, may Allah be pleased with them both, that the Noble Prophet, peace and blessings be upon him, said: "I see that your dreams coincide with each other regarding the last seven nights, so whoever among you wants to seek Laylat al-Qadr should seek it in the last seven nights."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4499