Jami' at-Tirmidhi 29

حَدَّثَنَا ابْنُ أَبِي عُمَرَ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ عَبْدِ الْكَرِيمِ بْنِ أَبِي الْمُخَارِقِ أَبِي أُمَيَّةَ، عَنْ حَسَّانَ بْنِ بِلاَلٍ، قَالَ رَأَيْتُ عَمَّارَ بْنَ يَاسِرٍ تَوَضَّأَ فَخَلَّلَ لِحْيَتَهُ فَقِيلَ لَهُ أَوْ قَالَ فَقُلْتُ لَهُ أَتُخَلِّلُ لِحْيَتَكَ قَالَ وَمَا يَمْنَعُنِي وَلَقَدْ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يُخَلِّلُ لِحْيَتَهُ ‏.‏

Hassan bin Bilal said:"1 saw Ammar bin Yasir performing Wudu, so he went through his beard (with his hand). It was said to him" - or he said - "1 said: 'You go through your beard?' He said: 'And what is there to prevent me? Indeed I saw Allah's Messenger going through his beard

Reference

Jami' at-Tirmidhi 29

In-book

Book 1, Hadith 29