Musannaf Ibn Abi Shayba 3:6308

Ibn Idris narrated to us, from al-Ajalih, from al-Sha'bi, from Zirr ibn Hubaysh, who said: I heard Ubayy ibn Ka'b saying: "It is the night of the twenty-seventh. It is the night about which the Messenger of Allah (may Allah bless him and grant him peace) informed us, that the sun rises on it white, shimmering."