Sayyiduna Tammam bin al-Abbas (may Allah be pleased with them both) narrates: The Prophet (peace and blessings be upon him) said: "Why is it that you people have come to me like this (i.e. without using the siwak)? Use the siwak! Were it not that I feared I would burden my Ummah with hardship, I would have commanded them to use the siwak at every purification (i.e. ablution)."
Imam Ahmad and Imam al-Tabarani (in al-Mu'jam al-Kabir) recorded this report, and these are his words. Its chain contains a narrator, Abu Ali al-Sayqal, and he is majhul (unknown).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1121
Hadith Gradingمحدثین:إسنادہ ضعیف
Hadith Takhrij«أخرجه مسند أحمد برقم: 1838، وأخرجه المعجم الكبير للطبراني برقم: 1302»