كتاب الحج
20  
Hajj

Yahya related to me from Malik from Nafi that Abdullah ibn Umar said, when nicking the hump of his sacrificial animal to brand it, "In the name of Allah, and Allah is greater."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ إِذَا طَعَنَ فِي سَنَامِ هَدْيِهِ وَهُوَ يُشْعِرُهُ قَالَ بِسْمِ اللَّهِ وَاللَّهُ أَكْبَرُ ‏.‏
USC-MSA web (English) reference : Book 20, Hadith 147
Arabic reference : Book 20, Hadith 850