If a person mistakenly recited Al Ha’mihya in a situation where he was required to recite Birkat Ha’mazon, must he now recite Birkat Ha’mazon? The Beracha of Al Ha’mihya is recited over grain products other than bread, whereas one who eats bread is required to recite the full Birkat Ha’mazon. If a person ate bread and mistakenly recited Al Ha’mihya, must he then recite Birkat Ha’mazon, or do we say that he fulfilled his obligation through his recitation of Al Ha’mihya?
Rabbi Moshe Halevi (Israel, 1961-2001), in his work Birkat Hashem (vol. 2, p. 270; listen to audio recording for precise citation), cites authorities who maintain that the Torah obligation of Birkat Ha’mazon does not require reciting three separate Berachot. Although the Birkat Ha’mazon we recite indeed consists of three separate Berachot (and a fourth Beracha which was introduced at a later point), this format was instituted by the Sages. As far as Torah law is concerned, however, one fulfills his obligation even by reciting a single Beracha, provided that this Beracha incorporates the themes of the three Berachot of Birkat Ha’mazon. This is the view of Maran (author of the Shulhan Aruch), both in his Bet Yosef (Orah Haim 191) and in his Kesef Mishne (Hilchot Berachot 2:2).
According to this view, then, one who mistakenly recited Al Ha’mihya when he was to have recited Birkat Ha’mazon has indeed fulfilled his obligation. Since the Beracha of Al Ha’mihya makes mention of the main themes of the three Berachot of Birkat Ha’mazon, it suffices, on the level of Bedi’abad (after the fact), to fulfill the obligation of Birkat Ha’mazon. Therefore, in such a case, one is not required to recite Birkat Ha’mazon, as he has fulfilled his obligation by reciting Al Ha’mihya.
Of course, it would be admirable in this case to wash one’s hands and eat another portion of bread so that he can recite Birkat Ha’mazon and thereby satisfy all opinions. According to the strict Halacha, however, this is not necessary, as he has fulfilled his obligation by reciting Al Ha’mihya.
Summary: If one mistakenly recited Al Ha’mihya instead of Birkat Ha’mazon, he does not then recite Birkat Ha’mazon. If he wishes to be stringent, he should wash his hands, eat another portion of bread, and then recite Birkat Ha’mazon.
