Hadith No: 1

As for the tradition which is narrated from Abdur Rahman bin Abi Umairah then it has a weak chain

Narrated 'Abdur-Rahman bin Abu 'Umairah - and he was one of the Companions of the Messenger of Allah (s.a.w.a.):

from the Prophet (s.a.w.a.), that he said to Mu'awiyah: "O Allah, make him a guiding one, and guide (others) by him."

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Al-Mubarakpoori - Tohfatul Ahwazi Be Sharh Jam'e al-Tirmidhi - Sharh of Sunan al-Tirmidhi

In Kitab al-Manaqeb - Chapter of the excellence of Muaviyah bin Sufiyan

volume 10, page 230, footnote number 1

... Abdur Rahman bin Abi Umairah al-Mazni and he was called al-Azdi - there are conflicting views whether he was a companion of Holy Prophet (s.a.w.a.)

In Tahzeeb al-Tahzeeb: Tirmidhi has narrated a single tradition from him mentioning Muaviyah

Hafiz says, Ibn Abd al-Barr says, he was not a companion of Holy Prophet (s.a.w.a.) and the chain of his tradition is incorrect.

Hafiz says, its chain is incorrect as we know from the biography of Abdur Rahman bin Abi Umairah 

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Reference: Sunan al-Tirmidhi Book 49 Tradition No. 4213

Hadith No: 2
Ibn Hajar al-Asqalani - Tahdhib al-Tahdhib - Continuation of the Chapter on the Letter 'Ayn
Those Named Abd al-Rahman - 491: Abd al-Rahman ibn Abi Umayra al-Mazni
Volume: (6) - Page Number: (243/244)
[The text is lengthy, so only the relevant excerpt is provided here]
491 - (al-Tirmidhi) Abd al-Rahman ibn Abi Umayra al-Mazni, and it is said that he was al-Azdiy: this is an error. He lived in Homs and narrated from the Prophet (peace be upon him and his holy progeny), and among those who narrated from him were Jubayr ibn Nufayr, Yunus ibn Maysurah ibn Halaybis, Rabi'ah ibn Yazid, and Khalid ibn Ma'dan. Al-Qasim Abu Abd al-Rahman has one hadith with al-Tirmidhi about Mu'awiyah. I say: Ibn Abd al-Barr stated that his companionship (with the Prophet) is not authentic, nor is the chain of his hadiths reliable, and Ahmad ibn Abd al-Rahim ibn al-Barqi was adamant that he was indeed an Azdiy, contrary to what the author conveyed.

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Reference: Tazheeb al Tahzeeb Book 6

Hadith No: 3
Ibn Hajar al-Asqalani - Taqreeb al-Tahdheeb - Letter 'Ayn - Mention of Those Named Abdul-Rahman
Volume: (1) - Page Number: (347)

3971 - Abdul-Rahman ibn Abi Umairah al-Mazni, and it is said: al-Azdhi, there is a difference of opinion regarding his companionship (with the Prophet). He settled in Homs.

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Reference: Taqreeb al Tahzeeb Book 1