" خَالِفُوا الْمُشْرِكِينَ: أَوْفِرُوا اللِّحَى وَأَحْفُوا الشَّوَارِبَ "
Ibn ‘Umar reported God’s messenger as saying, "Do the opposite of what the polytheists do ; let the beard grow long and clip the moustache.” A version has, “Cut the moustache down and leave the beard.” (Bukhari and Muslim.)