In Defense of the Sabbath

Abraham Ibn Ezra, under the influence of an inspiration or vision he had on that Shabbat day, decided to defend the traditional reckoning of the Jewish calendar, in which the day begins from nightfall rather than at day break, against biblical commentaries suggesting that the Sabbaths and festivals should begin in the morning. Immediately after the Sabbath he began to write his Iggeret Shabbat (“Letter of the Sabbath”) in which he used both religious and astronomical sources to defend his position. He wrote it while visiting England, making this one of the few Hebrew works composed there prior to the expulsion of the Jews in 1290.