The seventh day after leaving Egypt (ostensibly on a 3-day travel visa), the Israelites reached the Sea of Reeds with the Egyptian chariots on their heels. Therefore in shul this morning we sing the Song of the Sea (part of which is the "mi chamocha" that we chant during the Shma at shacharit and maariv). (Of interest to calligraphers: Shirat Hayam is one of the sections of the Torah that must be scribed in a certain way in a Torah scroll.)

A well-known midrash is that as the Egyption legions were drowning, God reproved them for rejoicing while his creations were being killed. But this interpretation is contested:

. . . the "Rasag", Rabeinu Sa’adia Gaon, one of the great Gaonim who lived after the period in which the Talmud was written . . . used the name "Chag HaHashmada" - The Holiday of Destruction, in reference to the Seventh Day of Passover. And indeed, after a little thought, the reason for such a name is simple: The seventh day of Passover was the day when the Egyptians were drowned in the Red Sea, and for this a "Yom Tov" was set down. Thus, the name: The Holiday of Destruction. . . . .

* Attention must be paid to the fact that the continuation (the next sentence) of the same Talmud says: "He (G-d) is not happy, but He commands others (Israel) to be happy." In other words, only G-d is not happy, since He cannot be joyful that he is forced to destroy the works of His hands, but He demands of us that we rejoice over the destruction of the enemies of Israel, which is a "Kiddush Hashem." The fact is, Israel certainly did sing the great song which we all know - the song of the sea - which we recite every morning.

* Other parallel "midrashim" teach us that G-d’s words concerning the people drowning in the sea were referring to the Jews, who at that moment were crossing the sea and had not yet been saved. This becomes clear after seeing "midrashim" which say: "Yisrael was in trouble in the sea" ("Tanchuma"), or "My hosts are in trouble" ("Shmot Raba", 23).

In any case, the point is clear that the entire "Yom Tov" of the seventh day of Passover is for the drowning of the evil enemy, which is a "Kiddush Hashem", as it says in the "Mechilta": "When the Almighty punishes the wicked, His name is made Great and Holy."

This is pretty harsh, especially in the Omer week of Chesed, but well within Judiasm's ethical range.