Barack Obama sent out his final Passover greeting as US president on Friday, recalling his 2009 tradition-making seder — the first ever at the White House, and drawing a parallel between the story of the Israelites’ Exodus from Egypt and the battle for civil rights across the globe. “Mah nishtana halailah hazeh?,” the president wrote, quoting the Four Questions asked during the Jewish service on the first night of Passover. The Hebrew phrase means: “Why is this night different from all other nights?” The president continued: “For Michelle and me, this Passover is different from all other Passovers because it...