كتاب الطهارة
Read the English translation first, with the original Arabic directly underneath.
It was narrated that Zaid bin Arqam said:
"The Messenger of Allah (ﷺ) said: 'Whoever does not trim his mustache, he is not from one of us.'"
مَنْ لَمْ يَأْخُذْ شَارِبَهُ فَلَيْسَ مِنَّا