Anas bin Malik reported,

The Prophet ﷺ sacrificed two horned rams of mixed black and white color. He slaughtered them with his own hand, mentioned the name of Allah, said the takbir, and placed his foot on their sides.In another narration, he said, "In the name of Allah, and Allah is the greatest."

Azami 11138

Sahih

عن أنس قال

ضحى النبي ﷺ بكبشين أملحين أقرنين ذبحهما بيده وسمى وكبر، ووضع رجله على صفاحهما. وفي رواية: ويقول: باسم الله، والله أكبر.

الأعظمي 11138صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Supplications, remembrances, and prayer upon the chosen Prophet ﷺ
Chapter
Supplications related to zakat, fasting, Hajj, slaughter, hunting, and transactions
Section
Saying Bismillah and takbir when slaughtering
Numbering
Jami al-Kamil 11138 (2nd edition)
Azami 11138