Yiḥyah Qafiḥ (Hebrew: רבי יחיא בן שלמה קאפח also Yiḥyah ibn Shalomo el Qafiḥ) (1850–1931), known also by the affectionate name "Ha-Yashish" (English: "the Elder"), served as the Chief Rabbi of Sana'a, Yemen in the late nineteenth and early twentieth centuries. He was one of the foremost rabbinical scholars in Sana'a during that period, and one who advocated many reforms in Jewish education. He was also learned in astronomy and in the metaphysical science of rabbinic astrology, as well as in Jewish classical literature which he taught to his young students.
Rabbi Qafih, in his youth, studied under Rabbi Yiḥya b. Yosef al-Qāreh, and received his ritual-slaughtering license from him in 1870. Although Rabbi Yihya Qafih served for only one year (1899–1900) as the Chief Rabbi of Yemen (Turk. Ḥakham Bāshī), he was a permanent member of the rabbinic court in Sana'a until his death, serving with the Chief Jurist and Rabbi, Yihya Yitzhak Halevi (d. 1932), whose signatures appear together in many of the court documents and responsa issued in the first quarter of the 20th century. In the late 19th century, he was the host to the Austrian Arabist and archeologist, Eduard Glaser, who conducted research in Yemen, and at the turn of the 20th century, he carried on a written correspondence with the Chief Rabbi of Ottoman Palestine in Jaffa, Rabbi Abraham Isaac Kohen Kook, in which he and his fellow jurists answered twenty-six questions posed to the Court at Sana'a.
Rabbi Qafiḥ had served as one of the chief instructors in the city's largest seat of learning (yeshiva), held then in the synagogue known as Bayt Saleḥ, until a famine in 1905, resulting from a war with the Ottoman Turks, forced the closure of the yeshiva. In the spring of 1906, Rabbi Yihya Qafiḥ was confirmed by the ruling monarch as one of four representatives of the Jewish community in Sana'a, along with Harun al-Cohen, Yiḥya Yitzḥak Halevi and Yiḥya al-Abyadh. The document outlined the obligations of the Jewish community toward the Muslim State and the Poll Tax (Ar. al-jizya) assessed against every male 13 years of age and older. In 1909, he became the headmaster of a Jewish school built by the Ottoman Turks in Sana'a, known as al-Makktab He initiated many reforms in Jewish education, such as teaching arithmetic and geography alongside the Torah, and employing Turkish teachers in the school for teaching the Turkish language to Jewish youth. One of the failures of the school, according to Yemen's last Chief Rabbi, Rabbi Amram Qorah, was that by teaching the Turkish language, their study of Hebrew suffered, seeing that the Jewish youth had less time to fully acclimate themselves to the rules of Hebrew grammar and to the finesse of the language. During this time, the controversy over the study of the Zohar worsened. After being incarcerated twice by Muslim authorities in 1914, being released only in Adar of 1915, Rabbi Qafiḥ regretted his earlier reticence in not speaking out against certain ills of the community. He began to be more vociferous about the people's neglect of Halacha for more mystical matters. It was around this time that he augmented the Dor Deʻah movement in Orthodox Judaism, to counter the influence of Lurianic Kabbalah and restore the rational approach to Judaism, such as is represented by the thought of Maimonides and Sa'adiah Gaon, and to encourage strict adherence to the Halakha as formulated in the Mishneh Torah. However, the innovations and textual readings enacted by Rabbi Qafih in his Beit midrash were the main cause for the schism in Sanaa's Jewish community, a schism that was fanned perpetually by "highly spirited youth." Since the Darda'im were interspersed in all the synagogues in Sana'a, the proprietors of those synagogues feared that this would lead to changes in their own rituals and customs, which they strongly opposed.