صحيح مسلم
Sahih Muslim
كتاب الأضاحي
The Book of Sacrifices
باب نَهْيِ مَنْ دَخَلَ عَلَيْهِ عَشْرُ ذِي الْحِجَّةِ وَهُوَ مُرِيدُ التَّضْحِيَةِ أَنْ يَأْخُذَ مِنْ شَعْرِهِ أَوْ أَظْفَارِهِ شَيْئًا.
Chapter: When the first ten days of Dhul-Hijjah begin, it is forbidden for the one who wants to offer a sacrifice to remove anything from his hair, nails or skin
Hadith 1977
This hadith is listed as number 5119 in Maktaba Shamila
وحَدَّثَنِي حَجَّاجُ بْنُ الشَّاعِرِ ، حَدَّثَنِي يَحْيَي بْنُ كَثِيرٍ الْعَنْبَرِيُّ أَبُو غَسَّانَ ، حَدَّثَنَا شُعْبَةُ ، عَنْ مَالِكِ بْنِ أَنَسٍ ، عَنْ عُمَرَ بْنِ مُسْلِمٍ ، عَنْ سَعِيدِ بْنِ الْمُسَيِّبِ ، عَنْ أُمِّ سَلَمَةَ ، أَنَّ ّالنَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ، قَالَ : " إِذَا رَأَيْتُمْ هِلَالَ ذِي الْحِجَّةِ وَأَرَادَ أَحَدُكُمْ أَنْ يُضَحِّيَ ، فَلْيُمْسِكْ عَنْ شَعْرِهِ وَأَظْفَارِهِ " .
Umm Salamah reported (these words) directly from Allah's Messenger (ﷺ) : If anyone has in his possession a sacrificial animal to offer as a sacrifice (on 'Id al-Adha), he should not get his hair cut and nails trimmed after he has entered the first days of Dhu'l Hijja
