(Suhayli says...
(Suhayli says: Ibn Ishaq did name the man, but Ibn Hisham preferred not to do so, as not to mention one of the Prophet's companions in discreditable circumstances. Therefore it can never be right to inquire after his identity. Abu Dharr says: Ibn Ishaq did name the man and said, “This man was Uthman b. Affan.” The Cairo editors say that in the Mawahib al-Laduniya, al-Qastallani, d. A.D. 1517, said that the man is said to be Uthman b. Mazun.
This latter writer may safely be ignored on this point.) “ At the site of the construction of the mosque, one may witness a most touching scene in the story of the early days of Islam – Muhammad Mustafa, the Messenger of God, removing dust, with his own hands, from the head and the face of Ammar ibn Yasar. He did not honor any other companion with a sign of such affection, love and tenderness.
When the Apostle of God reproved his companions for meddling with Ammar, and said that he (Ammar) was inviting them to paradise whereas they were inviting him to hell, he (the Apostle) was, most probably, paraphrasing the 41st verse of the 40th chapter (Sura-tul-Momin) in Qur’an which reads as follows: And o my people! How strange it is for me to call you to salvation while you call me to the fire.
Commenting upon this verse, Abdullah Yusuf Ali, the translator of Al-Qur’an al-Majid, says: It may seem strange according to the laws of this world that he should be seeking their good while they are seeking his damnation; but that is the merit of Faith. The companion who tangled with Ammar ibn Yasir when the mosque of Yathrib was being built, was no one other than Uthman b. Affan, one of the future khalifas of the Muslims.
He was squeamish about working in dust and mud, and getting his clothes soiled. When the Apostle of God showed him his displeasure, he had to keep quiet but the incident rankled in his heart, and he never forgot it. Many years later when he became khalifa, and found power in his hand, he ordered his slaves to knock down Ammar ibn Yasir and to beat him up – the man who was as dear to Muhammad Mustafa, the Apostle of God, as his (the Apostle's) own face.
The claim that it was not Uthman bin Affan but Uthman bin Mazun or somebody else who, by threatening Ammar ibn Yasir, roused the anger of the Apostle of God, is only an attempt at window-dressing by the “court” historians of later times.