Hadith 1320
Chapter 63: It is recommended to sacrifice the camel when it is standing and tied - كتاب الحج
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا خَالِدُ بْنُ عَبْدِ اللَّهِ، عَنْ يُونُسَ، عَنْ زِيَادِ بْنِ جُبَيْرٍ، أَنَّ ابْنَ عُمَرَ، أَتَى عَلَى رَجُلٍ وَهُوَ يَنْحَرُ بَدَنَتَهُ بَارِكَةً فَقَالَ ابْعَثْهَا قِيَامًا مُقَيَّدَةً سُنَّةَ نَبِيِّكُمْ صلى الله عليه وسلم .
Ziyad b. Jubair reported that Ibn 'Umar came upon a person who was slaughtering (sacrificing) his camel and had made him kneel down. So he told him to make it stand up festered (and then sacrifice it) according to the Sunnah of the Prophet (ﷺ).
Reference : Sahih Muslim 1320
In-book reference : Book 15, Hadith 397
USC-MSA web (English) reference : Book 7, Hadith 3032