Sahih Muslim Book 22, Hadith Number 4842.

Chapter : It is meritorious to sacrifice the animal with one’s own hand and so is meritorious the recitation of Bismillah (in the name of Allah) and Takbir (Allah o-Akbar).

Anas reported that Allah’s Messenger (may peace be upon him) sacrificed two horned rams of white colour with black markings over them. He also stated: I saw him sacrificing them with his own hand and saw him placing his foot on their sides, and recited the name of Allah and Glorified Him.