Bulugh al-Maram, Book 16, Hadith 1514 (English)

Ibn ’Umar (RAA) narrated that the Messenger of Allah said: “He who imitates any people (in their actions) is considered to be one of them.” Related by Abu Dawud and Ibn Hibban graded it as Sahih.

وَعَنِ اِبْنِ عُمَرَ ‏-رَضِيَ اَللَّهُ عَنْهُمَا‏- قَالَ: قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{ مَنْ تَشَبَّهَ بِقَوْمٍ, فَهُوَ مِنْهُمْ } أَخْرَجَهُ أَبُو دَاوُدَ, وَصَحَّحَهُ اِبْنُ حِبَّانَ.‏ (1930)‏.‏ ‏1 ‏- صحيح.‏ رواه أبو داود (4031)‏.‏

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also referenced under: Book 16, Hadith 1471 (In-Book)