Volume 2 · Book 15 · Hadith 73
Narrated Anas bin Malik,: Allah's Apostle never proceeded (for the prayer) on the Day of 'Id-ul-Fitr unless he had eaten some dates. Anas also narrated: The Prophet used to eat odd number of dates.
— Sahih Bukhari, Volume 2, Book 15: The Two Festivals (Eids), Hadith #73