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). (Using translation from Muslim 1977c)   

رَسُولَ اللهِ ﷺ قَالَ إِذَا دَخَلَ الْعَشْرُ وَأَرَادَ أَحَدُكُمْ أَنْ يُضَحِّيَ فَلَا يَمَسَّ مِنْ شَعْرِهِ وَلَا بَشَرِهِ شَيْئًا قِيلَ لِسُفْيَانَ فَإِنَّ بَعْضَهُمْ لَا يَرْفَعُهُ قَالَ لَكِنِّي أَرْفَعُهُ  

[Machine] The Messenger of Allah ﷺ said, "When the ten days of Dhul Hijjah begin and one of you intends to offer a sacrifice, let him refrain from cutting his hair and nails."  

قَالَ رَسُولُ اللهِ ﷺ إِذَا دَخَلَ الْعَشْرُ فَأَرَادَ أَحَدُكُمْ أَنْ يُضَحِّيَ فَلْيُمْسِكْ عَنْ شَعْرِهِ وَأَظْفَارِهِ  

[Machine] "O son of my brother, this is a hadith that has been forgotten and left. Umm Salama, the wife of the Prophet ﷺ, told me that the Messenger of Allah ﷺ said, 'Whoever has a sacrificial animal and intends to sacrifice it, then when the crescent moon of Dhul-Hijjah appears, let him not touch any of his hair or nails until he has sacrificed it.'"  

يَا ابْنَ أَخِي هَذَا حَدِيثٌ قَدْ نُسِيَ وَتُرِكَ حَدَّثَتْنِي أُمُّ سَلَمَةَ زَوْجُ النَّبِيِّ ﷺ عَنْ رَسُولِ اللهِ ﷺ قَالَ مَنْ كَانَ عِنْدَهُ ذَبْحٌ يُرِيدُ أَنْ يَذْبَحَهُ فَإِذَا أَهَلَّ هِلَالُ ذِي الْحِجَّةِ فَلَا يَمَسَّ مِنْ شَعْرِهِ وَلَا ظُفُرِهِ شَيْئًا حَتَّى يُضَحِّيَ  

[Machine] Is there any obligation? It means taking from the hair and nails. It was said that Malik narrated from Abdullah ibn Abi Bakr from Amrah from Aisha, she said, "I braided the necklaces of the gift of the Messenger of Allah ﷺ with my own hands, then the Messenger of Allah ﷺ braided them with his own hands, and then he sent them with my father and nothing was forbidden for the Messenger of Allah ﷺ that Allah made lawful for him until he slaughtered the sacrifice." Al-Shafi'i, may Allah have mercy on him, said, "In this there is evidence for what I described and that a person is not prohibited by the mission with his sacrifice."  

لَا وَاجِبٌ؟ يَعْنِي الْأَخْذَ مِنَ الشَّعْرِ وَالظُّفُرِ قِيلَ لَهُ رَوَى مَالِكٌ عَنْ عَبْدِ اللهِ بْنِ أَبِي بَكْرٍ عَنْ عَمْرَةَ عَنْ عَائِشَةَ ؓ قَالَتْ أَنَا فَتَلْتُ قَلَائِدَ هَدْيِ رَسُولِ اللهِ ﷺ بِيَدِي ثُمَّ قَلَّدَهَا رَسُولُ اللهِ ﷺ بِيَدِهِ ثُمَّ بَعَثَ بِهَا مَعَ أَبِي فَلَمْ يَحْرُمْ عَلَى رَسُولِ اللهِ ﷺ شَيْءٌ أَحَلَّ اللهُ لَهُ حَتَّى نَحَرَ الْهَدْيَ قَالَ الشَّافِعِيُّ رَحِمَهُ اللهُ وَفِي هَذِهِ دَلَالَةٌ عَلَى مَا وَصَفْتُ وَعَلَى أَنَّ الْمَرْءَ لَا يُحْرِمُ بِالْبِعْثَةِ بِهَدْيِهِ يَقُولُ الْبِعْثَةُ بِالْهَدْيِ أَكْثَرُ مِنْ إِرَادَةِ الضَّحِيَّةِ  

I twisted the garlands of the Hadis (i.e. animals for sacrifice) of Messenger of Allah ﷺ with my own hands. Then Messenger of Allah ﷺ put them around their necks with his own hands, and sent them with my father (to Mecca). Nothing legal was regarded illegal for Messenger of Allah ﷺ till the animals were slaughtered. (Using translation from Bukhārī 2317)   

أَنَا فَتَلْتُ قَلَائِدَ هَدْيِ رَسُولِ اللهِ ﷺ بِيَدِي ثُمَّ قَلَّدَهَا رَسُولُ اللهِ ﷺ بِيَدَيْهِ ثُمَّ بَعَثَ بِهَا مَعَ أَبِي بَكْرٍ ؓ ثُمَّ لَمْ يَحْرُمْ عَلَى رَسُولِ اللهِ ﷺ شَيْءٌ كَانَ أَحَلَّهُ اللهُ لَهُ حَتَّى نَحَرَ الْهَدْيَ أَخْرَجَاهُ فِي الصَّحِيحِ مِنْ حَدِيثِ مَالِكٍ