Volume 5, Book 57, Number 64:
Narrated Marwan bin Al-Hakam:
While I was with ‘Uthman, a man came to him and said, “Appoint your successor.” ‘Uthman said,
“Has such successor been named?” He replied, “Yes, Az-Zubair.” ‘Uthman said, thrice, “By Allah! In –
deed you know that he is the best of you.”