Musnad Ahmad 26:758

Zakariya ibn 'Adi narrated to us, he said: 'Ubayd Allah narrated to us, from 'Abd al-Karim, from Abu al-Wasil, from Ibn Mas'ud, from the Messenger of Allah, may Allah bless him and grant him peace, who said: "The one who performs the *tahlil* (the intermediary who marries a divorced woman to make her lawful for her first husband) and the one for whom it is performed are cursed."