Grading: (1) This report is sahih, and it is a chain whose narrators are thiqah.
Technical note / Defect ('illah): Except that Salih bin Ibrahim bin Abd al-Rahman bin Awf did not meet his grandfather Abd al-Rahman; in this report his father Ibrahim is the link between them. (Also) Abu Thabit: he is Muhammad bin Ubayd Allah bin Muhammad al-Umawi al-Madani.

Reference / Source: Imam al-Bukhari (2301) recorded it from Abd al-Aziz bin Abd Allah, from Yusuf bin Ya'qub al-Majishun, from Salih bin Ibrahim bin Abd al-Rahman bin Awf, from his father, from his grandfather Abd al-Rahman bin Awf.
Important point: So (in al-Bukhari's narration) he added "Ibrahim bin Abd al-Rahman bin Awf", by which the chain became connected.

Corroborating chains and supporting reports: Likewise a group narrated it from Ibn al-Majishun, among them Ibrahim bin Hamzah al-Zubayri in al-Bayhaqi's "Dala'il al-Nubuwwah" (30/ 90), and Ali bin Muslim al-Tusi in Ibn Asakir (7/ 29).

Note / Clarification: And see the discussion that preceded at no. (5419).

Note / Clarification: It preceded at no. (2580) that Umayyah bin Khalaf called Abd al-Rahman bin Awf by another name, "Abd al-Ilah"; see the discussion of this difference there.