Musnad Ahmad 928:31

Abdullah narrated to us, he said: Rawh ibn Abd al-Mu'min al-Muqri' narrated to us, he said: al-Hajjaj ibn Abi al-Furat, the brother of al-Furat ibn Abi al-Furat, narrated to us, he said: 'Asim narrated to us, from Zirr, from Ubayy ibn Ka'b, who said: "The Night of Decree is the night of the twenty-seventh, when three [nights] remain." And he did not attribute it to the Prophet (marfu').