Grace After Meals
Parshat עקב has two sections that discuss the specialness and beauty of Eretz Yisrael. After mentioning that it is a land that does not lack anything, the sections ends with the words, ואכלת ושבעת וברכת, that you shall eat, be satisfied and bless.
This is the source of the biblical commandment to recite ברכת המזון, the Grace after Meals. It consists of three Torah blessings, and one rabbinic blessing.
We acknowledge that Hashem sustains us, הזן את הכל, we thank Hashem for giving us Eretz Yisrael, על הארץ ועל המזון. And we pray that Jerusalem should be rebuilt, ובנה ירושלים.
A fourth blessing of הטוב והמטיב was added by the Rabbis to give thanks for the burial of those slain in Beitar.
When we say the after blessing for eating מזונות, cakes and pastries, known as על המחיה, it is also referred to as ברכה מעין שלוש, the blessing that is the idea of the three. This means that על המחיה is a brief summary of the three biblical blessings in ברכת המזון. It is also worth noting that all blessings are rabbinic except for ברכת המזון.