In sum, the ḥadīth is authentic through all of its chains, and the soundest of them is the last one—Allah knows best.
This narration was transmitted as an exegesis of the verse, “His Kursī extends over the heavens and the earth” (Qur’an 2:255). It states explicitly that the Kursī (Footstool) is the greatest created thing after the Throne, that it is a distinct physical entity, and not a merely abstract notion. Hence it refutes those who interpret the term as meaning “sovereignty” or “expansive authority,” as appears in certain commentaries. As for the report attributed to Ibn ʿAbbās that it signifies “knowledge,” its chain is not sound, for it comes only through Jaʿfar ibn Abī al-Mughīrah from Saʿīd ibn Jubayr from him; Ibn Jarīr relates this version. Ibn Mundah remarked, “Ibn Abī al-Mughīrah is not strong in his narrations from Ibn Jubayr.”
Know, then, that nothing describing the Kursī is authentically established from the Prophet ﷺ other than this ḥadīth. The reports that it is the place where the Divine Feet rest, that it emits a creaking like the creaking of a new camel saddle, that four angels carry it—each angel having four faces—and that their feet stand upon the rock beneath the seventh earth, and so forth, are all unauthentic when traced back to the Prophet ﷺ; some of them are even weaker than others. I have documented a number of those reports in the annotations appended to the book “Mā Dalla ʿAlayhi al-Qurʾān Mimmā Yaʿḍudu al-Hayʾah al-Jadīdah al-Qawīmah al-Burhān,” which is printed at the end of the volume by the Islamic Office (al-Maktab al-Islāmī).