Musnad Ahmad 1018:77

Makki ibn Ibrahim narrated to us, al-Ja'id narrated to us, from Musa ibn Abd al-Rahman al-Khatmi, that he heard Muhammad ibn Ka'b while he was asking Abd al-Rahman, saying: "Inform me of what you heard your father say about the Messenger of Allah, may Allah bless him and grant him peace." Abd al-Rahman said: "I heard my father say: I heard the Messenger of Allah, may Allah bless him and grant him peace, say: 'The likeness of one who plays with dice and then stands to pray is like the likeness of one who performs ablution with pus and the blood of a swine, and then stands to pray.'"