Bishr bin Suhaym (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) sent him during the days of Tashriq to announce that "these are days of eating and drinking, and none will enter Paradise except a believer."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8464