Nehar Mitzrayim (“The River of Egypt”) is an early 20th-century work of laws and customs followed by Egyptian Jewry, by the former chief rabbi of Cairo, Rabbi Raphael Aharon ben Shimon. It follows the order of the Shulchan Arukh, but omits financial laws covered in the Choshen Mishpat section of the Shulchan Arukh because Egyptian Jews followed secular authorities on financial matters. The work incorporates a wide range of earlier sources and extensively addresses social, legal, and technological issues facing the community. It often describes commonly accepted practices, like drinking coffee before morning prayers (when generally, eating before prayers is considered forbidden), examining the practices in light of earlier halakhic sources and ben Shimon’s own reasoning.