Ya'la ibn Murra reported that he heard Abu Hurayra speaking about someone who plays backgammon and bets on it, saying that he is like someone who eats pig meat and that the person who plays it without betting on it is like someone who washes his hands in pig's blood. The person who sits looking at it is like someone who looks at pig's meat.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا ابْنُ الصَّبَّاحِ، قَالَ: حَدَّثَنَا إِسْمَاعِيلُ بْنُ زَكَرِيَّا، عَنْ عُبَيْدِ بْنِ أَبِي أُمَيَّةَ الْحَنَفِيِّ هُوَ الطَّنَافِسِيُّ، قَالَ: حَدَّثَنِي يَعْلَى أَبُو مُرَّةَ قَالَ: سَمِعْتُ أَبَا هُرَيْرَةَ فِي الَّذِي يَلْعَبُ بِالنَّرْدِ قِمَارًا: كَالَّذِي يَأْكُلُ لَحْمَ الْخِنْزِيرِ، وَالَّذِي يَلْعَبُ بِهِ مِنْ غَيْرِ الْقِمَارِ كَالَّذِي يَغْمِسُ يَدَهُ فِي دَمِ خِنْزِيرٍ، وَالَّذِي يَجْلِسُ عِنْدَهَا يَنْظُرُ إِلَيْهَا كَالَّذِي يَنْظُرُ إِلَى لَحْمِ الْخِنْزِيرِ.
sunnah.com