Musannaf Ibn Abi Shayba 22:280

Al-Fadl ibn Dukayn narrated to us, from Sufyan, who said: Someone who heard Abu al-Aliyah mention it informed me, From Abu al-Jald, who said: The scrolls of Ibrahim were revealed on the first night of Ramadan, the Zabur (Psalms) was revealed on the sixth, the Injil (Gospel) on the eighteenth, and the Qur’an on the twenty-fourth.