Mu'jam Kabir Tabarani 9548 — I said to Sayyiduna Ubayy bin Ka'b: Tell

Zirr said: I said to Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him): Tell me about Laylat al-Qadr, for Sayyiduna Abdullah (bin Mas'ud) (may Allah be pleased with him) says: Whoever stands (in night prayer) the whole year will find it. He said: "May Allah have mercy on Abu Abd al-Rahman; he knows that it is in Ramadan, but he kept the matter vague for the people so that they would not rely (on it). By Allah, it is the twenty-seventh night." I said: O Abu al-Mundhir, how did you come to know that? He said: "By the sign that the Messenger of Allah (peace and blessings be upon him) told us of; so we counted and remembered that it is indeed that (night)." Asim said: I asked Zirr: What is that sign? He said: "The sun rising white, like a basin, without strong rays, until it rises high." The narrator said: I watched it like that many times.