Sahih al-bukhari:3717 Chapter: The virtues of the Companions of the Prophet ﷺ Book 62, Hadith 65

Narrated Marwan bin Al-Hakam: `Uthman bin `Affan was afflicted with severe nose-bleeding in the year when such illness was
prevelant and that prevented him from performing Hajj, and (because of it) he made his will. A man
from Quraish came to him and said, “Appoint your successor.” `Uthman asked, “Did the people name
him? (i.e. the successor) the man said, “Yes.” `Uthman asked, “Who is that?” The man remained
silent. Another man came to `Uthman and I think it was Al-Harith. He also said, “Appoint your
successor.” `Uthman asked, “Did the people name him?” The man replied “Yes.” `Uthman said, “Who
is that?” The man remained silent. `Uthman said, “Perhaps they have mentioned Az-Zubair?” The man
said, “Yes.” `Uthman said, “By Him in Whose Hands my life is, he is the best of them as I know, and
the dearest of them to Allah’s Messenger (ﷺ) .”