Al-Mughira ibn Shu'ba said: “I was a guest one night together with Allah’s Messenger (Allah bless him and give him peace), so he was brought a grilled flank. Then he took the blade and set about carving, and he carved some for me. Bilal arrived calling him to prayer, so he threw the blade away, and he said: ‘Why have his hands been soiled?’ His mustache hung down close to his mouth, so he said to him: ‘I shall clip it for you over a tooth-stick,’ or: ‘Clip it over a tooth-stick'!”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مَحْمُودُ بْنُ غَيْلانَ، قَالَ: حَدَّثَنَا وَكِيعٌ، قَالَ: حَدَّثَنَا مِسْعَرٌ، عَنْ أَبِي صَخْرَةَ جَامِعِ بْنِ شَدَّادٍ، عَنِ الْمُغِيرَةِ بْنِ عَبْدِ اللهِ، عَنِ الْمُغِيرَةِ بْنِ شُعْبَةَ، قَالَ: ضِفْتُ مَعَ رَسُولِ اللهِ صلى الله عليه وسلم ذَاتَ لَيْلَةٍ، فَأُتِيَ بِجَنْبٍ مَشْوِيٍّ، ثُمَّ أَخَذَ الشَّفْرَةَ فَجَعَلَ يَحُزُّ، فَحَزَّ لِي بِهَا مِنْهُ، قَالَ: فَجَاءَ بِلالٌ يُؤْذِنُهُ بِالصَّلاةِ فَأَلْقَى الشَّفْرَةَ، فَقَالَ: مَا لَهُ تَرِبَتْ يَدَاهُ؟، قَالَ: وَكَانَ شَارِبُهُ قَدْ وَفَى، فَقَالَ لَهُ: أَقُصُّهُ لَكَ عَلَى سِوَاكٍ أَوْ قُصُّهُ عَلَى سِوَاكٍ.
sunnah.com