The Prophet ﷺ said, "Whoever does not trim his moustache is not one of us."
حدثنا يحيى بن سعيد عن يوسف بن صهيب عن حبيب بن يسار
عن النبي ﷺ قال من لم يأخذ من شاربه فليس منا
Its isnad is sahih. Yusuf bin Suhayb and Habib bin Yasar al-Kindi are both trustworthy, and their biographies have already been mentioned. The hadith has already appeared at 19160.