Abu al-Huwayrith reports that the Prophet (peace and blessings be upon him) wrote to Sayyiduna Amr bin Hazm (may Allah be pleased with him) when he was in Najran: "Pray Eid al-Adha early, pray Eid al-Fitr late, and admonish the people."
This is mursal; I searched for it in all the narrations of his letter to Amr bin Hazm and did not find it, and Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة العيدين / 6149