Repentance from idol worship
During the holiday of Pesach (as well as every other holiday), we recite Hallel during the morning prayers. It consists of chapters 113 to 118 from Psalms. Chapter 114 describes how when the Jews left Egypt, nature was entirely subservient to them. Nothing stood in their way. Most pronounced was the miracle of the splitting of the sea. On the seventh day of Pesach, we commemorate this event with the Torah Reading being the Song at Sea that the Jews recited after this miracle. In Psalms the sea is described as “running away” from the Jews, meaning that it split in two, after seeing something. What did it see that made it split? Some say that it was Moshe. Others says that it was the coffin of Yosef. A very strange opinion is that the sea “saw” the teaching of the Academy of Rabbi Yishmael. What does this mean?
We know that while the Jewish people were in Egypt, they weren’t impervious to the latter’s influence. They too became idol worshippers, just like their Egyptian neighbors. The Jewish people’s idol worship was so intense, it was hard to distinguish them from the Egyptians. This was so much so, that the Angels didn’t understand why Hashem wanted to split the sea to save the Jews. They worshipped idols just as much as the Egyptians! Why should they merit a miracle and salvation?
However, we know that Hashem took no heed to their claims. The sea split for the Jewish people, and they were able to find safe haven from the Egyptians after crossing it. The reason is because Hashem knew that the Jewish people had repented. Part of the process of selecting a sheep for their Pesach offering was to also remove themselves from their idol worshipping ways. Proper repentance is always accepted, even in the face of the horrible crime of idol worship. Since the Jews were no longer sinners, Hashem split the sea for them. If so, why didn’t the Angels take this into account? Didn’t they know that the Jews had repented?
We are taught that Yishmael, the son of Avraham, was also guilty of idol worship. At the same time, we are taught that Yishmael properly repented. How do we know that his repentance was accepted by Hashem? Well, there’s a concept that the names of the wicked shall rot. What this means is that we do not name people after wicked individuals. The outcome of this is if we find a prominent Jew named after Yishmael, that would be proof that his repentance was accepted. Do we find such a thing? The name Yishmael doesn’t seem to be so common these days…
Back to the topic we started with, the sea did not want to split. The Angels, including the Angel in charge of the sea, saw that the Jewish people were no better than the Egyptians. These people worshipped idols, as well as these people. This was their claim, despite the fact that the Jews had already sincerely repented. It must be that the Angels thought that repentance may work for other sins, but not in the face of idol worship. It’s too much of an affront to Hashem’s honor to be forgiven. To correct this mistake, the sea “saw” the teaching of the Academy of Rabbi Yishmael. Meaning, the Angels were given a vision of the future, that there will one day be a great Rabbi in the Jewish people named Rabbi Yishmael. The fact that he is named after Yishmael, the son of Avraham, is proof that sincere repentance for idol worship is accepted by Hashem. Once this mistake was corrected, the sea immediately split. The Jewish people found salvation, because sincere repentance is always accepted, no matter how heinous the crime.
Chag Sameach and have a Good Yom Tov!
 Based on Gevilei Aish Haggadah Shel Pesach § במדרש הים ראה וינס, by Rav Simcha Bunim Sofer, son of the Cheishev Sofer, who was the son of the Da’as Sofer, who in turn was the son of the Sheivet Sofer, the son of the Kesav Sofer, who was the son of the Chasam Sofer. I found it printed in the back of a new edition of the Cheishev Sofer Derashos, Likkutim. Rav Avraham Sofer, the Gevilei Aish’s first cousin twice removed, also addressed this specific Midrash, translated here: https://parshaponders.com/pesach-5779-2
 This verse is referring to the ים סוף, often translated as the Red Sea, but more correctly as the Reed Sea
 Psalms 114:3
 Exodus 15:1-18. This is because the sea split on the Jews’ seventh day of their journey
 Megillah 31a; Shulchan Aruch Orach Chaim 490:5
 Shemos Rabbah 21:8. Others there suggest either the merit of Avraham or Yaakov
 Literally: the bones of Yosef
 Mechilta D’Rabbi Yishmael Masechta D’Vayehi § 3; Bereishis Rabbah 87:8; Midrash Tehillim § 114:4. In Sotah 37a (with Maharsha ad. loc.) it’s said to be either the tribe of Binyomin or Nachshon Ben Aminadav’s act of jumping in the sea that caused it. Mechilta also brings an opinion that it was either in the merit of Yerushalayim or the Twelve Tribes. Mechilta loc. cit. § 5 and Mechilta D’Rashbi 14:20 bring the same dispute as in Sotah as to who jumped in first. Pirkei D’Rabbi Eliezer Chapter 42 and Bamidbar Rabbah 13:7 only say Nachshon was the first to enter the sea. Interestingly, Shemos Rabbah 24:1 says the tribe of Yehudah were the first. Perhaps the intent is like Mechilta loc. cit., which brings an opinion that Nachshon went in first, and the rest of his tribe followed. Midrash Tehillim 76:1 brings a dispute if it was Nachshon, or if the story went that the tribe of Binyomin tried to enter, but the tribe of Yehudah beat them to it. Midrash Tehillim 114:4 says the tribes were fighting about who would get to enter first, and Binyomin and Yehudah were neck in neck. The sea saw that the Jews were fighting to sanctify Hashem’s name, and decided to split
 This Midrash is brought by the Chasam Sofer in Toras Moshe I, end of parshas Tzav under LeShevii shel Pesach s.v. ויבקעו המים במדרש רבה and הים ראה וינס, and Derashos II p. 269 col. 4 s.v. ראיתי, the latter citing Zera Yaakov (Katan). The source for this Midrash is unclear. One sefer I found claimed the earliest source they found for it is Tzafenas Paneach Chadash § Kayin VeHevel UKrias Yam Suf (published 1694), in the name of a certain sage
 The Gevilei Aish uses the phrase הללו עובדי עבודה זרה והללו עובדי עבודה זרה, which I heave heard quoted in many contexts. This phrase does not seem to have a source in Chazal. The closest is the Zohar II p. 170b, although that’s the Aramaic version of this phrase, and it adds both also were guilty of illicit relations and murder. The closest in Hebrew is Shemos Rabbah 21:7, but it only says said that the Jews until recently were idol worshippers, with no mention of the Egyptians. See also Shir HaShirim Rabbah 2:1, 8:8 that the ministers of the nations in the future will claim against the Jews אלו עבדו עבודת כוכבים ואלו עבדו עבודת כוכבים, and Midrash Tehillim 1:18, 15:3 that the nations in the future will claim אלו עובדי עבודה זרה ואלו עובדי עבודה זרה
 See Mechilta to Exodus 12:21
 Tosefta Sotah 6:3 and Bereishis Rabbah 53:11, brought by Rashi to Genesis 21:9
 Bava Basra 16b
 Proverbs 10:7
 Yoma 38b
 It’s very interesting then that in Bereishis Rabbah loc. cit., it is Rabbi Yishmael who teaches that Yishmael was guilty of idol worship (whereas in the Tosefta loc. cit. it was Rabbi Akiva who taught this)