وَعَنْ أُمَيَّةَ بْنِ مَخْشِيٍّ رَضِيَ اللَّهُ عَنْهُ قَالَ: كَانَ رَجُلٌ يَأْكُلُ، فَلَمْ يُسَمِّ حَتَّى لَمْ يَبْقَ مِنْ طَعَامِهِ إِلَّا لُقْمَةٌ، فَلَمَّا رَفَعَهَا إِلَى فِيهِ، قَالَ: بِسْمِ اللَّهِ أَوَّلَهُ وَآخِرَهُ، فَضَحِكَ النَّبِيُّ ﷺ، ثُمَّ قَالَ: «مَا زَالَ الشَّيْطَانُ يَأْكُلُ مَعَهُ، فَلَمَّا ذَكَرَ اسْمَ اللَّهِ، اسْتَقَاءَ مَا فِي بَطْنِهِ».
Translation: Umayyah ibn Makhshi relates that a man ate without mentioning Allah’s name until only one morsel remained. As he raised it toward his mouth, he said, “In Allah’s name, at its beginning and its end.” The Prophet ﷺ laughed and explained that Satan had been eating with him, but when he mentioned Allah’s name, Satan vomited what was in his belly.
The account teaches correcting a forgotten practice as soon as one remembers. لُقْمَةٌ means “a morsel,” فِيهِ “his mouth,” and اسْتَقَاءَ “he vomited.”
Source: Abu Dawud