In Judaism, mizrah (Hebrew: מזרח "east") is the direction to be faced during prayer. The word also designates the wall of the synagogue facing this direction, where seats are reserved for the rabbi and other dignitaries, and an ornamental wall plaque used to indicate the direction of prayer in Jewish homes.
The custom is based on the prayer of Solomon (I Kings 8:33, 44, 48; II Chron. 6:34). Another passage supporting this rule is found in the Book of Daniel, which relates that in the upper chamber of the house, where Daniel prayed three times a day, the windows of which were opened toward Jerusalem (Dan. 6:11).
The Tosefta demands that the entrance to the synagogue should be on the eastern side with the congregation facing west. The requirement is probably based on the orientation of the tent of meeting, which had its gates on the eastern side (Num. 2:2–3; 3:38), or Solomon's Temple, the portals of which were to the east (Ezek. 43:1–4). Maimonides attempted to reconcile the Tosefta's provision with the requirement to pray toward Jerusalem by stating that the doors of the synagogue should face east, while the Ark should be placed "in the direction in which people pray in that city," i.e., toward Jerusalem. The Shulkhan Arukh records the same rule, but it also recommends that one turn toward the southeast instead of east to avoid the semblance of worshiping the sun.
If a person is unable to ascertain the cardinal points, he should direct his heart toward Jerusalem.
Initially, the mizrah wall in synagogues was on the side of the entrance. However, the remains of the Dura-Europos synagogue on the Euphrates reveal that by the 3rd century C.E. the doors were on the eastern side and the opposite wall, in which a special niche had been made to place the scrolls during worship, faced Jerusalem. In Eretz Israel, the wall facing the Temple site was changed from the side of entrance to the side of the Ark in the 5th or 6th century. This change is found in synagogues at Naaran, near Jericho, and Bet Alfa. Worshipers came through the portals and immediately faced both the scrolls and Jerusalem.
Exception to the requirements of the Halakha still occur. The directions of the buildings frequently varied slightly due to the terrain. In the synagogues at Khirbat Summaqa, a village on the Mount Carmel, and at Usifiyya, where the orientations are not toward Jerusalem, and there is no satisfactory explanation for this divergence from the norm. With one exception, the ruins of synagogues in the Galilee were oriented from north to south, i.e. away from Jerusalem; most probably, the decision was made out of consideration for how the building would look from a distance. In Europe, synagogues were usually oriented toward the east, i.e. not exactly toward Eretz Israel, and congregations were very meticulous in choosing sites that would enable an eastward orientation.