seudah shlishit

Some explain that including Tzidkatekha after Minhah is because it is customary to eat Se'udah Shelishit ("the third meal"), and the Talmud states, "He who observes the three meals on the Sabbath is saved from three evils: the travails of the Massiah, the retribution of Gehinnom, and the wars of Gog and Magog."