His full name is Abu Ishaq Ahmed ibn Ibrahim al Tha’labi al Nishapuri (d. 227 A.H).
حدثنا حسن محمد بن حبيب المفسر قال وجدت فى كتاب جدى بخطه حدثنا احمد بن الاحجم القاضى المزوزى حدثنا الفضل بن موسى الشيبانى اخبرنا عبدالملك بن ابى سليمان عن عطية العوفى عن ابى سعيد الخدرى قال سمعت رسول الله صلى الله عليه و سلم يقول سلم انى قد تركت فيكم خليفتين ان اخذتم بهما لن تضلوا بعدى احدهما اكبر من الاخر كتاب الله حبل ممدود من السماء الى الارض وعترتى اههل بيتى الا انهما لن يتفرقا حتى يردا عللى الحوض
Hassan Muhammad ibn Habib al Mufassir says, “I found in my grandfather’s book, in his own handwriting, Ahmed ibn al Ahjam al Qadi al Marwazi — al Fadl ibn Musa al Shaybani — ‘Abdul Malik ibn Abi Sulaiman — ‘Attiyah al ‘Aufi — from Abu Sa’id that he heard Rasulullah salla Llahu ‘alayhi wa sallam saying:
O people, indeed I have left amongst you two successors. If you hold onto them, you will never go astray after me. One of them is greater than the other, the Book of Allah — a rope that has been extended from the sky to the earth — and my ‘itrah, who are my Ahlul Bayt. They will never separate until they meet me at the pond.”
There are two individuals in this isnad whose presence renders it unreliable in the light of the principles. The first one is Ahmed ibn al Ahjam and the second one is ‘Attiyah al ‘Aufi. Their details are as follows.
Hafiz Ibn Hajar and Hafiz al Dhahabi, after mentioning his fabricated narrations, quote from Ibn al Jawzi:
احمد بن الاحجم المروزى…قال فيه ابن الجوزى قالوا كان كذابا
The Muhaddithin regarded him (Ahmed ibn al Ahjam al Qadi) to be a flagrant liar.
The second individual is ‘Attiyah al ‘Aufi. His complete profile and exact status has been explained under the isnad of Tabaqat ibn Sa’d. ‘Attiyah is an unreliable narrator. He was a Shia. The Muhaddithin considered him unworthy of being used as a proof. He gave his teacher Muhammad ibn al Sa’ib al Kalbi (an infamous fabricator) the agnomen Abu Sa’id to deceive them into thinking that he was narrating from the famous Sahabi Abu Sa’id al Khudri radiya Llahu ‘anhu. He motive behind this was so that the people could accept his narrations without any hesitance. In this way, he spread these narrations amongst the masses. The narrations of such narrators cannot be accepted under any circumstances.
 ‘Abaqat al Anwar vol. 1 pg. 204-205
 Lisan al Mizan vol. 1 pg. 134 and Mizan al I’tidal vol. 1 pg. 38