It is narrated from Sayyiduna Abdullah bin Huzafah that the Prophet (peace and blessings be upon him) ordered him to announce during the days of Tashreeq that these are days of eating and drinking.
Hadith Referenceمسند احمد / مسند المكيين / 15735
Hadith Gradingحکم دارالسلام:مرفوعه صحيح لغيره، وهذا إسناد ضعيف لانقطاعه، سليمان بن يسارلم يدرك عبدالله بن حذافة