Sayyiduna Anas (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) did not go out on the day of Eid al-Fitr until he had eaten dates, 3, 5 or 7, or fewer or more than that, in an odd number.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة العيدين / 6155