Musnad Abu Ya'la al-Mawsili 160:254

Muhammad ibn Bakkar narrated to us, Ismail ibn Zakariyya narrated to us, from Asim al-Ahwal, from Abu Uthman, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) distributed dates, and I received five dates and a shriveled date (hashafah). He said: So I saw the shriveled date as the hardest of them for my molars.