(22) Clothing
كتاب اللباس
(4b) Chapter: Combing the Hair - Section 2
(3) باب الترجل - الفصل الثاني
Mishkat al-Masabih 4439 
‘Amr b. Shu'aib; on his father's authority, said his grandfather told that the Prophet used to take something off the side and the bottom of his beard. Tirmidhi transmitted it, saying this is a gharib tradition.
وَعَنْ عَمْرِو بْنِ شُعَيْبٍ عَنْ أَبِيهِ عَنْ جَدِّهِ: أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ يَأْخُذُ مِنْ لِحْيَتِهِ مِنْ عَرْضِهَا وَطُولِهَا. رَوَاهُ التِّرْمِذِيُّ وَقَالَ: هَذَا حَدِيثٌ غَرِيبٌ
 ضَعِيفٌ  (الألباني)حكم :
Reference : Mishkat al-Masabih 4439
In-book reference : Book 22, Hadith 128