Mishkat al-Masabih 22 Clothing كتاب اللباس 127

وَعَنْ زَيْدِ بْنِ أَرْقَمَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «مَنْ لَمْ يَأْخُذ شَارِبِهِ فَلَيْسَ مِنَّا» . رَوَاهُ أَحْمَدُ وَالتِّرْمِذِيُّ وَالنَّسَائِيُّ

Zaid b. Arqam reported God’s messenger as saying, “He who does not take something off his moustache is not one of us.” Ahmad, Tirmidhi and Nasa’i transmitted it.