Musnad Ahmad 928:19

Abdullah narrated to us, Abu Yusuf Yaqub ibn Ismail ibn Hammad ibn Zayd narrated to me, Abd al-Rahman ibn Mahdi narrated to us, Jabir ibn Yazid ibn Rifa’ah narrated to us, from Yazid ibn Abi Sulayman, who said: I heard Zirr ibn Hubaysh saying: "Were it not for your foolish ones, I would have placed my fingers in my ears, then I would have called out: 'Know that Laylat al-Qadr is in Ramadan, in the last ten nights, in the last seven nights, three nights before it, and three nights after it.'" [It is] a report from one who did not belie me, regarding a report from one who did not belie him. I said to Abu Yusuf: "Does he mean Ubayy ibn Ka'b, from the Prophet, may Allah bless him and grant him peace?" He said: "That is how it is with me."