Grading: (1) This report is sahih, and it is a chain whose narrators are acceptable (la ba'sa bihim).
Technical note / Defect ('illah): But there is disagreement over Sa'd bin Ibrahim in this chain regarding the identity of the narrator from Ali bin Abi Talib. Shu'bah narrates this report from Sa'd bin Ibrahim, from Ibrahim bin Qariz (who is Ibn Abd Allah bin Qariz), as in the author's (al-Hakim's) narration. But Ibrahim bin Sa'd bin Ibrahim bin Abd al-Rahman bin Awf contradicted him: he narrated the report from his father Sa'd bin Ibrahim, from his grandfather Ibrahim bin Abd al-Rahman bin Awf, from Ali bin Abi Talib, as will come with the author at no. (5430). So he mentioned his grandfather Ibrahim bin Abd al-Rahman bin Awf in place of Ibrahim bin Qariz.
Important point: And Ibrahim bin Abd al-Rahman bin Awf is the more reliable of the two men. In any case, whichever of them heard it from Ali, the report is sahih; and Allah knows best.
Corroborating chains and supporting reports: And Abd al-Rahman bin al-Hasan al-Qadi, even though there is some weakness in him, is corroborated (mutaba').

Reference / Source: Imam Ahmad recorded it in "Fada'il al-Sahabah" (1255) from Muhammad bin Ja'far, from Shu'bah, with this same chain.

Reference / Source: Ibn Abi Shaybah (12/ 95) recorded it via Mis'ar, from Sa'd bin Ibrahim: that Ali and Amr bin al-As (may Allah be pleased with them both) came to the grave of Abd al-Rahman bin Awf. He mentioned that one of them said: "Go, O Ibn Awf, for you attained its (this world's) clear part and went before its turbid part." And the other said: "Go, O Ibn Awf, for you have departed with your full share, having lost nothing of it."
Details of the narration: He mentioned it thus as "mursal".

Note / Clarification: "Al-ranaq" means: turbidity (murkiness).