"Do not fast on Saturday except in an obligatory fast, and if you find nothing but the bark of a tree, then break your fast with it." It was recorded by al-Ṭabarānī in "al-Muʿjam al-Kabīr" (8/303/7722): ʿAbd Allāh ibn Aḥmad ibn Ḥanbal narrated to us: al-Ḥakam ibn Mūsá narrated to me: Ismāʿīl ibn ʿAyyāsh narrated from ʿAbd Allāh ibn Dīnār from Abū Umāmah from the Prophet (ṣallá Allāhu ʿalayhi wa-sallam) who said... and he mentioned it. I said: This isnād [chain of transmission] consists of trustworthy men; however, there is a defect in it. Al-Haythamī said in "Majmaʿ al-Zawāʾid" (3/198): "It was narrated by al-Ṭabarānī in 'al-Kabīr' through the route of Ismāʿīl ibn ʿAyyāsh from the people of al-Ḥijāz, and he is weak among them." I said: It is as he said; however, Ismāʿīl ibn ʿAyyāsh has another authentic Syrian isnād. Imām Aḥmad said (6/368-369): al-Ḥakam ibn Nāfiʿ narrated to us: Ismāʿīl ibn ʿAyyāsh narrated from Muḥammad ibn al-Walīd al-Zubaydī from Luqmān ibn ʿĀmir from Khālid ibn Maʿdān from ʿAbd Allāh ibn Busr from his sister al-Ṣammāʾ with a similar narration. It is also included in "al-Irwāʾ" (4/121) from this route and others. This isnād is more authentic because al-Ḥakam ibn Nāfiʿ is a reliable and firm narrator, and al-Ḥakam ibn Mūsá is truthful as al-Ḥāfiẓ said in "al-Taqrīb," so the first isnād is authentic because Muḥammad ibn al-Walīd al-Zubaydī is a reliable and firm narrator. Ibn Nāfiʿ was followed by Ḍumrah ibn Rabīʿah from Ismāʿīl ibn ʿAyyāsh with it. It was recorded by al-Ṭabarānī in "Musnad al-Shāmiyyīn" (p. 317)