ENOfficial
‘Amr b. Shu'aib; on his father's authority, said his grandfather told that the Prophet (ﷺ) used to take something off the side and the bottom of his beard. Tirmidhi transmitted it, saying this is a gharib tradition.
Source: sunnah.com
Other translations
Arabic
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
sunnah.com