Musnad Ahmad 30:1512

Yunus narrated to us, Hammad—meaning Ibn Zayd—narrated to us, from al-Abbas ibn Farrukh al-Jurayri, who said: I heard Abu Uthman al-Nahdi saying: I was a guest of Abu Hurayrah for seven [days]. He, his wife, and his servant would take turns during the night in three parts; this one would pray, then wake that one, and this one would pray, then wake that one. He said: I said, "O Abu Hurayrah, how do you fast?" He said, "As for me, I fast three days from the beginning of the month; if something happens to me, it would be at the end of my month." He said: And I heard Abu Hurayrah saying: "The Messenger of Allah, may Allah bless him and grant him peace, divided dates among his companions one day, and I received seven dates, one of which was a shriveled date. There was nothing among them more pleasing to me than it, for it strengthened my chewing."