The one who wants to offer a sacrifice should not remove anything from his hair or nails during the ten (days at the beginning of Dhul-Hijjah)
حَدَّثَنَا هَارُونُ بْنُ عَبْدِ اللَّهِ الْحَمَّالُ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ حُمَيْدِ بْنِ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أُمِّ سَلَمَةَ، أَنَّ النَّبِيَّ ـ صلى الله عليه وسلم ـ قَالَ " إِذَا دَخَلَ الْعَشْرُ وَأَرَادَ أَحَدُكُمْ أَنْ يُضَحِّيَ فَلاَ يَمَسَّ مِنْ شَعَرِهِ وَلاَ بَشَرِهِ شَيْئًا " .
It was narrated from Umm Salamah that the Prophet (ﷺ) said: “When the ten days (of Dhul-Hijjah) begin, and one of you wants to offer a sacrifice, let him not remove anything from his hair or skin.”