Abu Zabyan narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both): I asked him about the saying of Allah Almighty: "And the sacrificial camels We have made for you among the symbols of Allah; for you therein is good. So mention the name of Allah over them when they are lined up (standing)" [Surah al-Hajj: 36]. He said: When you intend to slaughter the camel, make it stand, then say: 'Allahu akbar, Allahu akbar, Allahumma minka wa laka' (Allah is the Greatest, Allah is the Greatest; O Allah, it is from You and for You), then mention the name of Allah, then slaughter it. I asked: Do I say that for the sacrifice (udhiyah) as well? He said: And for the sacrifice too.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19186