Question: Is one obligated to sit while reciting Birkat Hamazon or is it permissible to recite it while walking as well?
Answer: The Gemara in Masechet Berachot (51b) states that one must recite Birkat Hamazon while seated. The Poskim as well as Maran Ha’Shulchan Aruch (Chapter 183) rule likewise: “One must sit while reciting Birkat Hamazon in order to engender maximum concentration.”
The Reason One Must Recite this Blessing Specifically while Seated
It seems that the reason one must sit while reciting Birkat Hamazon is in order for the individual to have optimum concentration while blessing. The reason why our Sages were more stringent regarding this blessing as opposed to other blessings (such as the “Shehakol Nihya Bidvaro” blessing which need not be recited while seated) is because reciting Birkat Hamazon is a Torah obligation, as we have discussed in a different Halacha.
The Difference Between Keri’at Shema and Birkat Hamazon
Based on the above, a question arises: Keri’at Shema is likewise a Torah obligation and even so, Shema may be recited while walking or standing. If so, why did our Sages rule stringently and require one to recite Birkat Hamazon specifically while seated?
The Tosafot and other Rishonim explain that the reason why our Sages treated Birkat Hamazon more stringently than Keri’at Shema is because the Torah obligation of reciting Shema applies only to the first verse (or the first chapter according to some opinions); indeed, this verse should not be recited while walking. However, the Sages did not rule so stringently to obligate one to recite the rest of Keri’at Shema while sitting, for it is not a Torah obligation.
Summary: Birkat Hamazon should not be recited while one is walking or standing; one must specifically be seated, for our Sages instituted that one sit in order for one to have maximum concentration while blessing.
We shall broaden this topic in the next Halacha.