Certain concepts are essential to Grace after Meals, and if they are not mentioned, the recitation is invalid. Among the concepts mentioned are covenant, Torah and sovereignty. The Gemara relates that not all of the Sages were in agreement regarding this requirement. Rav Hisda is quoted as telling Rabbi Zeira that he did not feel confident that he knew the laws of Grace after Meals. He explained this by means of the following story:
I happened to come to the house of the Exilarch and recited Grace after Meals, and Rav Sheshet stiffened his neck over me like a snake, i.e., he got angry and challenged me. Rabbi Zeira asked: And why did Rav Sheshet become angry with you? He answered: I did not mention covenant, Torah, or sovereignty in Grace after Meals.
Rabbi Zeira wondered: And why did you not mention those themes? He answered that he did so in accordance with the opinion that Rav Ḥananel said that Rav said: If one does not mention covenant, Torah or sovereignty in Grace after Meals, he nevertheless fulfilled his obligation because these themes are not applicable to all of Israel. Covenant does not apply to women; Torah and sovereignty apply neither to women nor to slaves.
RabbiZeira said to him: Rav Sheshet should have been angry with you. And you abandoned all of these tanna’im and amora’im who disagree with him, and followed Rav? Evidently, many tanna’im and amora’im hold that covenant, Torah, and sovereignty must be mentioned in the second blessing of Grace after Meals.
Many questioned why Rav Ḥisda recited Grace after Meals without mentioning covenant, Torah, and sovereignty, contrary to the virtually unanimous opinion of the Sages. Even if Rav Ḥananel permitted this after the fact, he did not prescribe to do so ab initio.
Some explain that Rav Ḥisda inadvertently neglected to mention covenant, Torah, and sovereignty. Once he did so, he did not return to mention it (Penei Yehoshua). Others explain that there were women and slaves reclining at that table, and he sought to recite a formula appropriate for all present (Tziyyun LeNefesh Hayya). Alternatively, he held that because women and slaves do not mention covenant and sovereignty, men should not mention them either to ensure a universally uniform formula for Grace after Meals (Rashba).