Salim (may Allah have mercy on him) narrates from his father (may Allah be pleased with him): "I saw the Prophet (peace and blessings be upon him), Abu Bakr (may Allah be pleased with him) and Umar (may Allah be pleased with him) walking in front of the funeral." (Ali bin al-Madini said:) So I stood up and went to him (Sufyan) and said: O Abu Muhammad, Ma'mar (may Allah have mercy on him) and Ibn Jurayj (may Allah have mercy on him) differ with you on this, meaning that they narrate the hadith from the Prophet (peace and blessings be upon him) as mursal. He said: Al-Zuhri was firm on it; he narrated it to me, I heard it from his own mouth, repeating it over and over, from Salim from his father. I said to him: O Abu Muhammad, Ma'mar and Ibn Jurayj say in it: 'and Uthman.' He confirmed what they said and said: Perhaps he did say it and I did not write it down, because at that time I was inclined towards the Shi'ah.
The Shaykh (al-Bayhaqi) said: There is disagreement on Ibn Jurayj and Ma'mar about whether this hadith is connected: it has been narrated from each of them connected (mawsul) and also mursal, and it has also been said: from Ibn Jurayj, from Ziyad bin Sa'd, from al-Zuhri.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6858