When any one of you intending to sacrifice the animal enters in the month (of Dhu'l-Hijja) he should not get his hair or nails touched (cut). It was said to Sufyan that some of the (scholars) did not deem this hadith to be Maffu'. He said: But I deem it as Marfu' (i. e. chain of narration traceable right up to the Holy Prophet).
أَنَّ النَّبِيَّ ﷺ قَالَ إِذَا دَخَلَتِ الْعَشْرُ وَأَرَادَ أَحَدُكُمْ أَنْ يُضَحِّيَ فَلاَ يَمَسَّ مِنْ شَعَرِهِ وَبَشَرِهِ شَيْئًا قِيلَ لِسُفْيَانَ فَإِنَّ بَعْضَهُمْ لاَ يَرْفَعُهُ قَالَ لَكِنِّي أَرْفَعُهُ