Sayyiduna Ali (may Allah be pleased with him) and Sayyiduna Khabbab (may Allah be pleased with him) report that the Prophet (peace and blessings be upon him) said: "When you are fasting, use the siwak (tooth-stick) in the morning and do not use it in the evening, for any fasting person whose lips become dry in the evening, that will be a light before his eyes on the Day of Resurrection."
Al-Tabarani recorded it in al-Mu'jam al-Kabir. He narrated it as marfu' (attributed to the Prophet) from Sayyiduna Khabbab (may Allah be pleased with him), and not as marfu' from Sayyiduna Ali (may Allah be pleased with him). Its chain contains Kaysan Abu Umar, whom Ibn Hibban declared thiqah (trustworthy), while others declared him da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصيام / 4954
Hadith Gradingمحدثین:إسناده ضعیف
Hadith Takhrij«اخرجه الطبراني فى المعجم الكبير (3696) ، أخرجه المعجم الكبير للطبراني برقم: 3696»