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) Sunan Ibn Majah 3149
Arabic hadith text
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 "
Translation
It wasnarrated from Umm Salamah that the Prophet (ﷺ) said
“Whentheten days (of Dhul-Hijjah) begin, and one of you wants to offer asacrifice, let him not remove anything from his hair or skin.”