Musnad Ahmad 928:13

Sufyan narrated to us, he said: I heard it from 'Abdah and 'Asim, from Zirr, who said: I asked Ubayy, I said: "O Abu al-Mundhir, your brother Ibn Mas'ud says: 'Whoever stands [in prayer] for the whole year will encounter the Night of Decree (Laylat al-Qadr).'" He said: "May Allah have mercy on him. He certainly knew that it is in the month of Ramadan, and that it is the night of the twenty-seventh." He said: And he swore [an oath]. I said: "And how do you know that?" He said: "By the sign or the token that the Messenger of Allah (ﷺ) informed us of: 'That the sun rises on that day without rays.'"