Sayyiduna Ghannam (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever fasts six days after Eid al-Fitr, it is as if he fasted all time and the whole year."
Al-Tabarani recorded it in al-Mu'jam al-Kabir. I do not know the narrator named Abd al-Rahman bin Ghannam.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصيام / 5104
Hadith Gradingمحدثین:إسناده ضعیف
Hadith Takhrij«أخرجه المعجم الكبير للطبراني برقم: 3905»