Grading: The hadith is sahih, and this chain is hasan solely on account of Muhammad bin Ishaq (Ibn Yasar al-Muttalibi).
Technical note / Defect ('illah): He explicitly stated that he heard it from Makhul in Ya'qub bin Sufyan's "al-Ma'rifah wa al-Tarikh" (1/461), which removes the suspicion of his tadlis. However, Abu Khalid al-Ahmar (Sulayman bin Hayyan) erred in narrating the hadith of Hisham bin al-Ghaz and Ibn Ajlan (Muhammad bin Ajlan) as connected, as Imam al-Daraqutni pointed out in "al-'Ilal" (1116). He said: I think Abu Khalid carried the hadith of Hisham bin al-Ghaz and Ibn Ajlan over onto the hadith of Muhammad bin Ishaq and so made its chain look sound, whereas others narrate it from Hisham and Ibn Ajlan, from Makhul, from Abu Dharr in mursal form. And Waki' said: from Hisham bin al-Ghaz, from Makhul, from the Prophet (peace and blessings be upon him) (in mursal form); he did not mention Abu Dharr. Then al-Daraqutni said: Muhammad bin Ishaq kept its chain sound (connected) from Makhul.

Technical note / Defect ('illah): We say: There is another problem in the chain of Abu Khalid al-Ahmar, namely his saying: "from Ghudayf bin al-Harith, from Abu Dharr" that a young man passed by Umar, whereas all those who narrated this story from Muhammad bin Ishaq said in their narration: "from Ghudayf bin al-Harith" that "I passed by Umar bin al-Khattab", and then he mentioned his story with Abu Dharr and what Abu Dharr told him about Umar. But this matter is minor, so what occurs in Abu Khalid's narration is to be understood as meaning that Ghudayf's words "from Abu Dharr" mean "about the story of Abu Dharr with me" and what he told me from the Messenger of Allah (peace and blessings be upon him) about Umar. Ghudayf may have left himself unnamed in this narration out of humility. In this way Abu Khalid's narration from Ibn Ishaq agrees with that of the other narrators. And Allah knows best.
Important point: This report is also authentically established through another route from Ghudayf bin al-Harith, that he passed by Umar bin al-Khattab, and he mentioned the story.

Reference / Source: Ahmad recorded it (35/21457) from Yazid bin Harun and (21542) from Ya'la bin Ubayd, Abu Dawud (2962) via Zuhayr bin Mu'awiyah, and Ibn Majah (108) via Abd al-A'la bin Abd al-A'la al-Sami. All four narrate it from Muhammad bin Ishaq with this chain.
Note / Clarification: Except that Zuhayr and Abd al-A'la confined themselves in their narration to the marfu' part and did not mention the story.

Reference / Source: Ahmad recorded it (21295) via Hammad bin Salamah, from Abu al-Ala' Burd bin Abi Ziyad, from Ubadah bin Nusayy, from Ghudayf bin al-Harith: that he passed by Umar, and he mentioned it. Its chain is sahih.

Note / Clarification: In manuscripts (S) and (M) the word is "dhira'an".

Note / Clarification: The text between the brackets is an addition that we have established from the takhrij sources, and it is indispensable.