There has been much ink spilled over a question raised by R’ Akiva Eiger regarding bentching. What is the din if a minor ate a meal before nightfall, bentched, but is still in a state of seviah, satiation, after dark when he turned bar mitzvah? Does he need to repeat bentching now that he is halachically an adult?
The question may hinge on what creates the obligation of birchas hamazon which we learn from the pasuk of “V’achalta v’savata u’beirachta…”:
1) Is it the act of eating, achila, which obligates one to bentch, and “v’savata” is just a description of the amount that needs to be consumed?
2) Is it “v’savata,” becoming satiated, which obligates one to bentch, provided that satiation comes from eating?
3) Is it a combination of both eating and feeling satiated?
If an act of eating is required to create an obligation to bentch, then one could argue that a halachic adult who has not eaten has no obligation to bentch. However, if satiation, “v’savata,” creates the obligation to bentch, then if that adult is satiated from having eaten, even if the act of eating took place when he was a minor, perhaps he must bentch.
The Magen Avraham similarly discusses a case where someone ate little bits at a time, which halachically does not constitute eating, but after doing this for awhile the person felt satiated – does he have an obligation to bentch? The question seems to hinge on the same issue of whether bentching depends on satiation alone or requires an act of eating.
One could argue that R’ Akiva Eiger’s case is a little different. An act of eating was done, albeit by a minor. Perhaps one could argue that the actions of a minor should not be dismissed as halachically insignifcant; even if there was no d'oraysa obligation on the minor to bentch, his act of eating may trigger such an obligation once he becomes bar mitzvah.