It wasnarrated from Anas bin Malik:
"The Messenger of Allah (ﷺ)used tosacrifice two horned, black-and-white rams and he would saythe Nameof Allah and pronounce His greatness. I saw him slaughteringthemwith his own hand, putting his foot on their sides." (JA)
English reference (JA): Vol. 4, Book 26, Hadith 3120 (JA)
Arabic reference (JA): Book 26, Hadith 3239 (JA)