Hadith 3:114
‘Uthman said that the Prophet used to make the water go through his beard. Tirmidhi and Darimi transmitted it.
وَعَنْ عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ: أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ يُخَلِّلُ لِحْيَتَهُ. رَوَاهُ التِّرْمِذِيّ والدارمي
Original Reference: Mishkat al-Masabih 409