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." (FR)
English reference (FR): Vol. 4, Book 26, Hadith 3120 (FR)
Arabic reference (FR): Book 26, Hadith 3239 (FR)