The verse in the book of Yeshaya (Chapter 58) states: “And you shall call Shabbat [a day of] pleasure.” We see from here that there is a Mitzvah for one to make Shabbat as enjoyable as possible through such things as eating and drinking tasty things.
Since this Mitzvah is not an explicit commandment from the Torah, rather it is understood from the words of the prophet Yeshaya, the Rambam writes that this is not a Torah obligation and is only a rabbinic commandment. Nevertheless, one should be meticulous with this Mitzvah, for its reward is great indeed, as the prophet (ibid.) continues, “Then Hashem shall bestow enjoyment upon you and I shall carry you on the heights of the land and I shall feed you the inheritance of your forefather, Yaakov, so has Hashem spoken.” The Gemara in Masechet Shabbat (118a) tells us that Rabbi Yochanan derived from this verse in the name of Rabbi Yose that “anyone who enjoys Shabbat shall be given a limitless inheritance.” The Gemara continues to enumerate several other great rewards for this Mitzvah.
Some Rishonim (such as the Rashba and the Rivash) write that this Mitzvah is actually a Torah commandment since Shabbat is considered one of the festivals mentioned by the Torah which the Torah calls “Proclamations of Holiness” and our Sages interpret this to mean that one must sanctify and honor the festivals by wearing clean clothes and enjoy them by eating and drinking. According to this opinion, one would have to intend to fulfill a Torah commandment while eating. Even according to the Rambam, one should at least have in mind to fulfill the Mitzvah of enjoyment of Shabbat while eating.
Some explain that this Mitzvah is a Torah commandment for although it is not mentioned explicitly in the Torah, nevertheless, our Sages treated it as a “Halacha Moshe learned at Mount Sinai” and it has the weight of a Torah commandment.
The following are the words of the Rambam (Chapter 30 of Hilchot Shabbat) which apply to our discussion: “What is considered enjoyment? This refers to what our Sages said that one must prepare a fatty cooked dish and spiced drink (i.e. delicious foods and tasty beverages) for Shabbat based on one’s financial status. The more one spends on the expenses of Shabbat and the preparation of delicacies, the more praiseworthy one is. If one cannot afford this, even if he has only prepared one simple cooked food in honor of Shabbat, this is considered his enjoyment of Shabbat.”
The Gemara speaks lengthily about the significance of one who causes Shabbat to be enjoyable and honors Shabbat based on one’s means. The Gemara recounts a story about a man named Yosef Mokir Shabbat (Yosef who honors the Shabbat). A wealthy gentile who lived in Yosef’s neighborhood and would commonly seek advice from astrologers and other fortune-tellers was once advised by such astrologers that his neighbor, Yosef the Jew, would receive all of his possessions. The wealthy man immediately sold all of his material possessions and used the money to buy a magnificent, priceless pearl that he had sewn into his hat so that his neighbor, Yosef, would not be able to get his hands on his possessions. One day, this wealthy man was walking on a bridge across a river and suddenly, a strong wind blew off his hat into the waters of the river below. A fish appeared and then swallowed this hat. It happened that the fishermen of this city caught this fish close to the start of Shabbat, but they wondered who would be willing to purchase this fish from them at such a late hour. They were told to go to Yosef for although he certainly had already prepared fish for Shabbat because of his intense honor for Shabbat, nevertheless, if he would be shown an especially beautiful fish, he would buy it. Indeed, when the fisherman showed Yosef this fish, he purchased it eagerly. While he was gutting and preparing the fish for cooking, he found a stunning pearl in its innards. Upon meeting “a certain elderly man” (whom some say is Eliyahu Ha’Navi who sometimes appears to righteous people), he was told that whoever borrows money in honor of Shabbat, the Shabbat itself pays back his debts.
Nevertheless, one should not borrow extensively in honor of Shabbat if one has no natural means to repay these debts.