Umar ibn Abu Salamah reported: I was under the care of the Messenger of Allah, peace and blessings be upon him, and my hand used to roam about the dish. The Prophet said to me, “O young man, mention the name of Allah, eat with your right hand, and eat what it is front of you.”

Source: Sahih Bukhari 5061, Sahih Muslim 2022

Grade: Muttafaqun Alayhi (authenticity agreed upon) according to Al-Bukhari and Muslim

http://dailyhadith.abuaminaelias.com/2013/07/22/hadith-on-food-remember-the-name-of-allah-and-eat-with-your-right-hand/