Ibrahim narrates from al-Aswad (may Allah have mercy on him) that Sayyiduna Abdullah (may Allah be pleased with him) said: Seek Laylat al-Qadr on the night of the seventeenth, (the night before) the morning of Badr, or the twenty-first, or the twenty-third.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8542