Midrash su Esodo 38:19

Our Rabbis taught: How many meals must a man eat on the Sabbath? "Three." But R. Chidka says "Four." R. Jochanan said: "Both the Rabbis and R. Chidka interpret the same passage. (Ex. 16, 25.) And Moses said. Eat it to-day; for a Sabbath is this day unto the Lord; to-day ye will not find it in the field. R. Chidka is of the opinion that the use of the word Hayom (day) [mentioned in the above passage] three times indicates three meals during the day excluding the evening meal; together with the Friday evening meal it makes four; but the Rabbis are of the opinion that the three meals include that of Friday night, hence there are but three altogether." (Fol. 118a) R. Simon b. Pazi in the name of R. Joshua b. Levi, who spoke in the name of bar Kappara, said: "He who fulfills the observation of three meals on the Sabbath, will be delivered from three evil dispensations, viz., from the pains of Messiah, from the judgment of Gehenna, and from the war of Gog and Magog. From the pains of Messiah, for it is written here (Ex. 16, 25.) Yom (day); and it is also written (Malachi 3, 23.) Behold. I will send you Elijah, the prophet, before the coming of the day (Yom) of the Lord, etc.; from the judgment of hell, here is written Yom (day) and (Zephanin 1, 15.) A day of wrath is that day (Yom); of the war of Gog ana Magog, here is written (Yom) (day) and it is written (Ex. 38, 19.) On the day (Yom) of Gog's comincg."