Musnad Ahmad 30:1168

Abu Amir narrated to us, Abdullah narrated to us, from Uthman ibn Muhammad, from al-Maqburi, from Abu Hurayrah, who said: "The Messenger of Allah cursed the one who marries a divorced woman to make her lawful for her former husband (al-muhallil), and the one for whom she is made lawful (al-muhallal lahu)."