Question: If one is unsure whether or not one has recited a blessing a food one is currently eating, must one recite the blessing again as a result of the doubt? If not, may one continue eating?
Answer: Our Sages taught us a great rule: “A doubt regarding a blessing is to be treated leniently” (i.e. when in doubt regarding a blessing, do not bless). This is as a result of the severity of the prohibition to recite a blessing in vain, for every blessing contains the name of Hashem and reciting Hashem’s name for naught is a grave sin. Thus, whenever a doubt exists regarding whether or not to recite a blessing, we rule that one should not recite the blessing. We have discussed this point on several different occasions. The basis for this is another teaching of our Sages in Masechet Berachot that “one who recites an unnecessary blessing (a blessing one is not obligated to recite) transgresses the prohibition of uttering Hashem’s name in vain.” The Rishonim disagree regarding the understanding of this Gemara, for according to the Tosafot (Rosh Hashanah 33a) and other Rishonim, the prohibition of reciting an unnecessary blessing is merely rabbinic and when the Gemara states that one who recites an unnecessary blessing has transgressed the prohibition of uttering Hashem’s name in vain, this does not refer to an actual Torah prohibition; rather, this is only a rabbinic prohibition which the Sages based on the verse of “Do not bear the name of Hashem, your G-d, in vain.”
On the other hand, the Rambam and other great Rishonim maintain that reciting an unnecessary blessing is an absolute Torah prohibition; thus, one who recites Hashem’s name within a blessing one is not obligated to recite has transgressed the prohibition of “Do not bear the name of Hashem, your G-d, in vain.” Maran Ha’Shulchan Aruch, whose rulings we follow, rules likewise that one who recites an unnecessary blessing has transgressed the Torah prohibition of uttering Hashem’s name in vain.
Based on this, the consensus of the Poskim is that when in doubt regarding a blessing, one must act leniently and abstain from reciting the blessing. Reciting the blessing as a result of the doubt is prohibited because by doing so, one is entering a situation of possibly uttering Hashem’s name in vain if one has, in fact, already recited this blessing. Indeed, the Rambam (Chapter 4 of Hilchot Berachot) rules: “If one is in doubt whether or not one has recited the ‘Hamotzi’ blessing, one should not recite this blessing again since this is not a Torah obligation.”
Maran Ha’Shulchan Aruch (Chapter 209) rules likewise: “Any blessing about which one is in doubt whether or not one has recited it, whether it is a blessing before or after eating, should not be recited again (besides for Birkat Hamazon which is a Torah obligation, as we have discussed elsewhere).”
Summary: If one is in doubt whether or not one has recited a blessing on the food one is currently eating, one should not recite the blessing again as a result of the doubt. In the following Halacha, we shall, G-d-willing, discuss whether or not one may continue to eat the food before him and if there is a way to rectify such a situation.