That the Prophet ﷺ said: "Whoever sees the crescent of Dhul-Hijjah, and wants to slaughter a sacrifice he should not take from his hair nor from his nails."  

عَنِ النَّبِيِّ ﷺ قَالَ مَنْ رَأَى هِلاَلَ ذِي الْحِجَّةِ وَأَرَادَ أَنْ يُضَحِّيَ فَلاَ يَأْخُذَنَّ مِنْ شَعْرِهِ وَلاَ مِنْ أَظْفَارِهِ