كتاب الأطعمة
Read the English translation first, with the original Arabic directly underneath.
Narrated Aisha, Ummul Mu'minin:
The Messenger of Allah (ﷺ) said: When one of you eats, he should mention Allah's name; if he forgets to mention Allah's name at the beginning, he should say: "In the name of Allah at the beginning and at the end of it."
إِذَا أَكَلَ أَحَدُكُمْ فَلْيَذْكُرِ اسْمَ اللَّهِ تَعَالَى فَإِنْ نَسِيَ أَنْ يَذْكُرَ اسْمَ اللَّهِ تَعَالَى فِي أَوَّلِهِ فَلْيَقُلْ بِسْمِ اللَّهِ أَوَّلَهُ وَآخِرَهُ