Musnad Ahmad 1017:45

Waki’ narrated to us, from Sufyan, from ‘Alqamah ibn Marthad, from Sulayman ibn Buraydah, from his father, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever plays with Nardshir (backgammon), it is as if he has dipped his hand into the flesh and blood of a swine." And Waki’ did not attribute it (to the Prophet) on one occasion.