Musannaf Ibn Abi Shayba 36:551

Ishaq al-Razi narrated to us, from Abu Ja'far, from Ayyub, from Nafi', from Ibn Umar, that Uthman woke up speaking to the people. He said: "I saw the Prophet, peace and blessings of Allah be upon him, tonight in a dream." He said: "O Uthman, break your fast with us." So he woke up fasting, and he was killed on that same day.