Tamim ibn Hadhlam said, "I will mention the first to be greeted as 'Amir' in Kufa. Al-Mughira ibn Shu'ba left by the Bab ar-Rahba and a man of Kinda came up to him. They claim that it was Abu Qurra al-Kindi. He greeted him and said, 'Peace be upon you, O Amir, and the mercy of Allah.' He disliked it. So the man said, 'Peace be upon you, O Amir, and the mercy of Allah. Peace be upon you. Am I one of you or not?'" Sammak ibn Salama ad-Dabi said, "After that it became an established practice."
Reference: Al-Adab Al-Mufrad 1026 In-book : Book 42, Hadith 63 English translation : Book 42, Hadith 1026
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