Sahih Muslim 1966
Sahih Muslim · Book 35: The Book of Sacrifices · It is recommended to select a good animal for the sacrifice and to slaughter it oneself, not delegating it to anyone else, and to say the name of Allah, and to say the Takbir
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى ، حَدَّثَنَا ابْنُ أَبِي عَدِيٍّ ، عَنِ سَعِيدٍ ، عَنْ قَتَادَةَ ، عَنْ أَنَسٍ ، عَنِ النَّبِيِّ صلى الله عليه وسلم بِمِثْلِهِ غَيْرَ أَنَّهُ قَالَ وَيَقُولُ " بِاسْمِ اللَّهِ وَاللَّهُ أَكْبَرُ " .
This hadith has been transmitted on the authority of Anas with a slight variation of wording.