Brachot 45 - Three people ate together
The Torah said, "And you shall eat, and be satisfied, and you shall bless God your Lord for the good Land that He gave you." We thus see that after a complete meal with bread, one must say a prayer containing thanks for the sustenance, for the Land of Israel and for Jerusalem (the good Land).
In addition, if three people ate together, they must call each other to join in this prayer. This is true even if the food they ate had some limitations. For example, in the case of food from which tithes may not have been separated - still, since one can renounce all his possessions, become poor, and be free of the obligation to tithe.
This joining in prayer removes the obstacles on the way of the prayer and allows it to rise up; and also brings an additional level of joy. What is the source for it? - It is this phrase: " When I proclaim God's name, praise God for His greatness ."
Art: Gillis Van Tilborch - Elegant company at a table on a terrace