Link 3 from the end of the chain
Narrated Abu Jamra: Ibn `Abbas said to us, "Shall I tell you the story of Abu Dhar's conversion to Islam?" We said, "Yes." He said, "Abu Dhar said: I was a man from the tribe of Ghifar. We heard that a man had appeared in Mecca, claiming to be a Prophet. ! said to my brother, 'Go to that man and talk to him and bring me his news.' He set out, met him and returned. I asked him, 'What is the news with you?' He said, 'By Allah, I saw a man enjoining what is good and forbidding what is evil.' I said to him, 'You have not satisfied me with this little information.' So, I took a waterskin and a stick and proceeded towards Mecca. Neither did I know him (i.e. the Prophet (ﷺ) ), nor did I like to ask anyone about him. I Kept on drinking Zam zam water and staying in the Mosque. Then `Ali passed by me and said, 'It seems you are a stranger?' I said, 'Yes.' He proceeded to his house and I accompanied him. Neither did he ask me anything, nor did I tell him anything. Next morning I went to the Mosque to ask about the Prophet but no-one told me anything about him. `Ali passed by me again and asked, 'Hasn't the man recognized his dwelling place yet' I said, 'No.' He said, 'Come along with me.' He asked me, 'What is your business? What has brought you to this town?' I said to him, 'If you keep my secret, I will tell you.' He said, 'I will do,' I said to him, 'We have heard that a person has appeared here, claiming to be a Prophet. I sent my brother to speak to him and when he returned, he did not bring a satisfactory report; so I thought of meeting him personally.' `Ali said (to Abu Dhar), 'You have reached your goal; I am going to him just now, so follow me, and wherever I enter, enter after me. If I should see someone who may cause you trouble, I will stand near a wall pretending to mend my shoes (as a warning), and you should go away then.' `Ali proceeded and I accompanied him till he entered a place, and I entered with him to the Prophet (ﷺ) to whom I said, 'Present (the principles of) Islam to me.' When he did, I embraced Islam 'immediately. He said to me, 'O Abu Dhar! Keep your conversion as a secret and return to your town; and when you hear of our victory, return to us. ' I said, 'By H him Who has sent you with the Truth, I will announce my conversion to Islam publicly amongst them (i.e. the infidels),' Abu Dhar went to the Mosque, where some people from Quraish were present, and said, 'O folk of Quraish ! I testify that None has the right to be worshipped except Allah, and I (also) testify that Muhammad is Allah's Slave and His Apostle.' (Hearing that) the Quraishi men said, 'Get at this Sabi (i.e. Muslim) !' They got up and beat me nearly to death. Al `Abbas saw me and threw himself over me to protect me. He then faced them and said, 'Woe to you! You want to kill a man from the tribe of Ghifar, although your trade and your communications are through the territory of Ghifar?' They therefore left me. The next morning I returned (to the Mosque) and said the same as I have said on the previous day. They again said, 'Get at this Sabi!' I was treated in the same way as on the previous day, and again Al-Abbas found me and threw himself over me to protect me and told them the same as he had said the day before.' So, that was the conversion of Abu Dhar (may Allah be Merciful to him) to Islam."
Link 3 from the end of the chain
Narrated Nafi`: Ibn `Umar used to give the Zakat of Ramadan (Zakat-al-Fitr) according to the Mudd of the Prophet, the first Mudd, and he also used to give things for expiation for oaths according to the Mudd of the Prophet. Abu Qutaiba said, "Malik said to us, 'Our Mudd (i.e., of Medina) is better than yours and we do not see any superiority except in the Mudd of the Prophet!' Malik further said, to me, 'If a ruler came to you and fixed a Mudd smaller than the one of the Prophet, by what Mudd would you measure what you give (for expiation or Zakat-al-Fitr?' I replied, 'We would give it according to the Mudd of the Prophet' On that, Malik said, 'Then, don't you see that we have to revert to the Mudd of the Prophet ultimately?'"