Sahih Muslim
The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness (Kitab Al-Dhikr)
Book Number: 035 / Hadith Number: 6592
Anas b. Malik reported that Allah's Messenger (may peace be upon him) said: Allah is pleased with His servant who says: Al-Hamdu lillah While taking a morsel of food tnd while drinking.