Musnad Ahmad 26:186

Abu Dawud al-Tayalisi narrated to us, Zuhayr narrated to us, Abu Ishaq narrated to us, from Sa’d ibn ‘Iyad, from ‘Abdullah, who said: "The most beloved part of the sheep to the Messenger of Allah, may Allah bless him and grant him peace, was the foreleg, the foreleg of the sheep. It had been poisoned in the foreleg, and he used to believe that it was the Jews who had poisoned it."