We were with the Prophet when food was presented to him, and I never saw food which had greater blessing when we began to eat, or less when we finished. We asked God’s messenger how that was, and he replied, “We mentioned God’s name when we ate, then one who ate sat down without mentioning God's name and the devil ate with him.”
Anas reported God’s messenger as saying, “God most high is pleased when a man eats something and praises Him for it, or drinks something and praises Him for it."
‘A’isha reported God’s messenger as saying, “When one of you eats and forgets to mention God over his food he should say, ‘In the name of God at the beginning and at the end of it’.”
Abu Umama told that when the Prophet's cloth* was removed he said, "Praise be to God abundantly and sincerely, of such a nature as is productive of blessing, is not insufficient, abandoned, or ignored, O our Lord."
*The word ma'ida means a piece of leather or some other material spread on the ground for the food, and it comes to mean the food itself. It is often translated ‘table’, but this is misleading with reference to the early days of Islam.