One morning back in my JTS days, a group of students was finishing up breakfast after morning minyan, getting ready to head to our first class of the day. A faculty member, beloved for his authenticity as a serious scholar and religious thinker, walked over to our table and pointed to a JTS bentscher–the small booklet containing Birkat Hamazon, the blessings after eating. He pointed to a photo of an ancient manuscript and asked, “Do you know what this is?” When we pleaded ignorance, he said: “It’s the oldest known version of Deuteronomy. And if you look closely, you’ll see that it says ve-akhalta (‘and you shall eat’) and vesavata (‘and you shall be satisfied’). But it doesn’t say uveirakhta (‘and you shall bless’), so you don’t really need to say Birkat Hamazon. Have a nice day.” Then he walked away. We all burst into laughter, not just at the joke, but at the mere fact that he told one!
Of course, that word isn’t missing from the text, and this verse (Deuteronomy 8:10) is the basis for the requirement to give thanks to God after eating. We quote it in Birkat Hamazon each time we recite those blessings. The Talmud shows how each component berakhah in that prayer corresponds to a word or phrase in the verse. But then they ask a question: “I only have a Torah source for blessings after eating; what’s the source for the need to say a berakhah before we eat? The answer is based not on a source, but on logical inference: “If, when one is satiated, one is obligated to thank God, how much the more so when one is hungry!” (Bavli Berakhot 48b).