Sahih Bukhari
Oneness, Uniqueness of Allah (Tawheed)
Volume: 009 / Book Number: 093 / Hadith Number: 495
Narrated 'Aisha:
The people said to the Prophet , "O Allah's Apostle! Here are people who have recently embraced Islam and they bring meat, and we do not know whether they had mentioned Allah's Name while slaughtering the animals or not." The Prophet said, "You should mention Allah's Name and eat."