Prophet Muhammad (sallallahu ‘alayhi wa sallam) said:
“The seven Heavens compared to the Kursee (the footstool) is like a ring which is thrown into a desert.
And such is the magnitude of the ‘Arsh (the Throne of Allah) compared with the Kursee.”
Saheeh: Related by Ibn Abee Shaybah in Kitaabul-‘Arsh (1/114)
and al-Bayhaqee in as-Asmaa was-Sifaat (p.290), from Abu Dharr (radiAllahu ‘anhu).
The hadeeth is authentic due to its various routes of transmission-as Shaykh al-Albaanee has explained in as-Saheeh (no.109).