Musannaf Ibn Abi Shayba 9:459

16362. Waki’ narrated to us, from Ibn Abi Layla, from his grandfather, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever deems lawful..." He said: And I heard Waki’ issuing a fatwa regarding it, saying: "He marries her for a dirham."