'Umar bin Abu Salamah (May Allah be pleased with him) reported:
I was a boy under the care of Messenger of Allah (ﷺ), and my hand would wander about in the dish. Messenger of Allah (ﷺ) said to me "Mention Allah's Name (i.e., say Bismillah before you start eating), eat with your right hand and eat from what is near to you". I always followed this way of eating after this incident.[Al-Bukhari and Muslim].
Arabic/English book reference: Book 1, Hadith 299