Amsterdam, where, after he and his son had been circumcised, his wife also converted to Judaism; they then went to the Land of Israel. According to Jewish tradition, following Avraham ben Avraham's death, the Vilna Gaon believed that the spiritual constitution of the world had become altered in such a way that a Jew was no longer bound to wash his hands in the morning (netilat yadayim) within four amot (cubits) of his bed, as explicitly taught in the codes of Jewish law such as the Shulchan Aruch and other halachic works. Rather, a Jew's entire house would be considered as four amot for this mitzvah. This custom, begun at Avraham ben Avraham's death, commenced with the Vilna Gaon and later became the practice of the Slabodka yeshiva in Europe, becoming today the routine of many leading Israeli rabbis who follow the Slabodka tradition. Lack of historical evidence Many secondary sources – encyclopaedias of Jewish culture, history and religion – include an entry on Potocki, a Polish magnate and member of the powerful Potocki family, who converted to Orthodox Judaism in 18th-century Netherlands and who, after his return to Vilna, was tried by an Inquisition court which sentenced him to burning at the stake. Historians (ex. Janusz Tazbir, Jacek Moskwa, Rimantas Miknys and Magda Teter) who have studied the story of Potocki, however, believe it to be invented, although it is unknown when or by whom (Moskwa points to a possibility that the author was Kraszewski himself, who is known to have invented some tales he claimed were true). Teter mentioned that the story ("a carefully crafted tale of conversion") was likely created and developed as a "response to a number of challenges that the Polish Jewish community faced from the mid-eighteenth century". Tazbir (2003) Polish historian Janusz Tazbir asserted that the story—he uses the term "legend"—originated at the turn of the 19th century and was published in a Jewish periodical issued in London as "The Jewish Expositor and Friend of Israel" (vol. 8, 1822). He notes that the literary version of the legend was created by Józef Ignacy Kraszewski, a well-known Polish writer of the 19th century, author of numerous historical novels, who included the story about Potocki in the third volume of the history of Vilna (1841), Wilno od początków jego do roku 1750 (1840–1842), in which he claims to have followed a Hebrew original, thought by some