al-Qasim ibn Muhammad القاسم بن محمد بن أبي بكر الصديق · The Book of ad-Dahaya (Sacrifices)

"I saw him: - meaning the Prophet - "slaughtering them with his own hand, and placing his foot on their sides, pronouncing the name of Allah and saying: 'Allah Akbar,' (sacrificing) two horned, Amlah rams." (Sahih )