It is narrated from Zirr with reference to Ubayy bin Ka'b (may Allah be pleased with him) that, by Allah, I have the most knowledge regarding the Night of Qadr. The night about which the Prophet Muhammad (peace and blessings be upon him) informed us in this regard is the twenty-seventh night of Ramadan.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 21195