Musnad Abu Ya'la al-Mawsili 152:303

Abu Khaythama narrated to us, Shuja’ ibn al-Walid ibn Qays narrated to us, Abu Khalid al-Dalani narrated to us, from Talq ibn Habib, from Abu Aqrab al-Asadi, who said: I came to Abdullah ibn Mas’ud while he was on a roof, and I sat upon it. He was saying, "Allah and His Messenger have spoken the truth. Allah and His Messenger have spoken the truth." He said: "The Messenger of Allah (may Allah bless him and grant him peace) informed us that the Night of Decree (Laylat al-Qadr) is in the middle of the last seven [nights], and that the sun rises on its morning without rays." So I climbed up and saw it as such, and I said, "Allah and His Messenger have spoken the truth."