The wine of Phrygia [Perugaita] and the water of the Deyomset deprived Israel of the ten lost tribes. Because the members of these tribes were attracted to the pleasures of wine and bathing and did not occupy themselves with Torah, they were lost to the Jewish people.
The Gemara relates that once Rabbi Eleazar ben Arakh happened to come there, to Phrygia and Deyomset, and he was drawn after them, and his Torah learning was forgotten. When he returned, he stood to read from a Torah scroll and was supposed to read the verse: “This month shall be for you [haḥodesh hazeh lakhem]”(Shemot12:2), but he had forgotten so much that he could barely remember how to read the Hebrew letters, and instead he read:
Have their hearts become deaf [haḥeresh haya libbam], interchanging the similar letters reish for dalet, yod for zayin, and beit for khaf. The Sages prayed and asked for God to have mercy on him, and his learning was restored.
And that is what we learned in a Mishna that Rabbi Nehorai says: Exile yourself to a place of Torah and do not say that it will follow you, as if you are in a place of Torah, your colleagues will establish it in your hands, and do not rely on your understanding alone. It was taught: Rabbi Nehorai was not his name, but rather Rabbi Neḥemya was his name; and some say that Rabbi Elazar ben Arakh was his name and his statement was based on the personal experience of forgetting his Torah due to his failure to exile himself to a place of Torah. And why was he called Rabbi Nehorai? It was because he would illuminate [manhir] the eyes of the Sages in halakha.
Rabbi Elazar’s error resulted from the similarity between the letters reish and dalet, yod and zayin, and beit and khaf. The Gemara relates the details of the error to underscore that even Rabbi Elazar ben Arakh, who was likened to an ever-flowing spring, reached so lowly a state when he left the company of the Sages (Maharsha).