Sahih Muslim , Book 30, Hadith 5750 (USC-MSA) ⓘ
Anas reported: I saw when the Messenger of Allah got his hair cut by the barber, his Companions came round him and they eagerly wanted that no hair should fall but in the hand of a person.
حَدَّثَنَا مُحَمَّدُ بْنُ رَافِعٍ، حَدَّثَنَا أَبُو النَّضْرِ، حَدَّثَنَا سُلَيْمَانُ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، قَالَ لَقَدْ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم وَالْحَلاَّقُ يَحْلِقُهُ وَأَطَافَ بِهِ أَصْحَابُهُ فَمَا يُرِيدُونَ أَنْ تَقَعَ شَعْرَةٌ إِلاَّ فِي يَدِ رَجُلٍ .
also referenced under: Book 43, Hadith 101 (In-Book) & Hadith 2325 (Reference)