Musnad Ahmad 30:2250

'Affan narrated to us, Hammad bin Zayd narrated to us, al-'Abbas al-Jurayri narrated to us, he said: I heard Abu 'Uthman al-Nahdi saying: I was a guest of Abu Hurayrah for seven [days]. He said: And I heard him saying: "The Prophet, may Allah bless him and grant him peace, distributed dates among his companions, and I received seven dates, one of which was a dried-up, hard date (hashafah). There was nothing more pleasing to me than it, for it strengthened my chewing."