Uthman, so I said: "Then you, O my father?" He said: "I am nothing but a man among the Muslims." (1)

4630 - Muhammad ibn Miskin narrated to us, Muhammad — meaning al-Firyabi — narrated to us: I heard Sufyan say: "Whoever claims that Ali was more entitled to the caliphate than the two of them has erred against Abu Bakr, Umar, the Muhajirun, and the Ansar, and I do not think that any deed of his will rise to heaven with this." (2)

4631 - Muhammad ibn Yahya ibn Faris narrated to us, Qabisa ibn Uqba narrated to us, Abbad al-Sammak narrated to us: I heard Sufyan al-Thawri say: "The caliphs are five: Abu Bakr, Umar, Uthman, Ali, and Umar ibn Abd al-Aziz, may God be pleased with them all." (3)

--------------------------------------------
(1) Its chain of transmission is sound. Abu Ya'la: he is al-Mundhir ibn Ya'la al-Thawri, and Sufyan: he is Sufyan ibn Sa'id al-Thawri, and Muhammad ibn Ghayr: he is al-Abdi.
Al-Bukhari also narrated it (3671) from Muhammad ibn Ghayr, with this chain of transmission.
Ibn Majah also narrated it in similar form (106) via the route of Abdullah ibn Salama, from Ali. And Ibn Salama is weak.
It is also in "Musnad Ahmad" (833) and (835).
Al-Hafiz in "al-Fath" 7/34 quoted al-Qurtubi: "What is definitively established among the people of the Sunnah is the superiority of Abu Bakr and Umar, then they differed regarding those after them. The majority hold the precedence of Uthman, and it is reported from Malik that he withheld judgment. The matter is one of ijtihad, and its basis is that God Almighty chose these four for the caliphate of His Prophet and the establishment of His religion, so their rank with Him is according to their order in the caliphate."

(2) Its chain of transmission to Sufyan — and he is al-Thawri — is sound, and Muhammad al-Firyabi: he is Ibn Yusuf.
Abu Nu'aym also narrated it in "al-Hilya" 7/31 via the route of Muhammad ibn Sahl ibn Askar, from Muhammad ibn Yusuf al-Firyabi, with it.

(3) Its chain of transmission is weak due to the unknown status of Abbad al-Sammak. Sufyan: he is al-Thawri.
Ibn Asakir also narrated it in "Tarikh Dimashq" 45/190 and 191 via the route of Qabisa ibn Uqba, with it.