Zirr bin Hubaish narrates: I said to Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him): O Abu'l-Mundhir, your brother Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: Whoever performs voluntary prayers at night throughout the year will attain Laylat al-Qadr. He replied: May Allah have mercy on him, he wants you not to rely on just one night, although Allah knows best that it is in the month of Ramadan, and it is in the last ten nights, and it is the twenty-seventh night. The narrator says: We said: O Abu'l-Mundhir! On what basis do you say this? He replied: Because of the sign, or the indication about which the Prophet (peace and blessings of Allah be upon him) informed us, that when the sun rises on that day, it has no rays.