Jami` at-Tirmidhi 2758
جامع الترمذي#2758Sahihحَدَّثَنَا إِسْحَاقُ بْنُ مَنْصُورٍ، أَخْبَرَنَا عَبْدُ الصَّمَدِ بْنُ عَبْدِ الْوَارِثِ، حَدَّثَنَا صَدَقَةُ بْنُ مُوسَى أَبُو مُحَمَّدٍ، صَاحِبُ الدَّقِيقِ حَدَّثَنَا أَبُو عِمْرَانَ الْجَوْنِيُّ، عَنْ أَنَسِ بْنِ مَالِكٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ وَقَّتَ لَهُمْ فِي كُلِّ أَرْبَعِينَ لَيْلَةً تَقْلِيمَ الأَظْفَارِ وَأَخْذَ الشَّارِبِ وَحَلْقَ الْعَانَةِ .
Narrated Anas:from the Prophet (ﷺ), that he (ﷺ) fixed the time as every forty nights for them to trimming the fingernails, taking from the mustache, and shaving the pubic hairs
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 43:28