Every Motzaei Shabbos, as is well known, it is appropriate to escort Shabbos as it leaves us, just as one accompanies a king as he leaves a city. That is why the special seuda held on Motzaei Shabbos is called Melave Malka, which means "accompanying the Queen."
Even if a person is going to eat only a kezayis, he should set the table for a full seuda, light candles, and sing zemiros, just as he would do in honor of a king. The AriZal taught that one should rejoice during this seuda as one does during the seudos of Shabbos.
The Rebbe points out that even after Havdala the Shabbos Queen has not yet completely left, for otherwise there would be no one to accompany...
(שו"ע אדה"ז סי' ש', שיחו"ק תשל"א ח"א ע' 301 )
Rebbi Abbahu had a choice calf prepared for him every Motzaei Shabbos, of which he only ate the kidneys. Seeing this, his son Avimi suggested that he take the kidneys from the calf that had been shechted on erev Shabbos, and thus save an entire animal. Rebbi Abbahu did as he advised, but a lion came and ate the second calf, which he had wanted to save. From this we learn to give Shabbos its full honor by serving fine food at Melave Malka.
(שבת קי"ט ע"ב)
On Motzaei Shabbos one should wear Shabbos clothing. Some do so until after Melave Malka; others, until they go to sleep. This was in fact the minhag of the Frierdiker Rebbe and the Rebbe, who also instructed others to do so. Reb Yehoshua of Belz once said: For as long as one wears his Shabbos clothing on Motzaei Shabbos, his stay in Gan Eden every Motzaei Shabbos will be extended.
(ראה ליקוט סעודת מלוה מלכה)
A Full Seudah
It is preferable to wash for HaMotzi in honor of the Melave Malka, though if one is unable to do so, he can fulfill the mitzva by eating other foods. The Rebbe always made a point of washing for Melave Malka.
The Rebbe explains that just as the Yidden in the midbar had their Melave Malka from the extra portion of Mon that they had received for Shabbos, a Melave Malka today completes the seudos of Shabbos and elevates them to the heights of an extraordinary mitzva.
(שו"ע אדה"ז סי' ש', לקו"ש חל"ו ע' 75 )
One Motzaei Shabbos, when the chassidim of Reb Dovid Moshe of Chortkov gathered for their Melave Malka, singing zemiros and exchanging stories of tzaddikim, the Rebbe himself unexpectedly made an appearance. He sat down with them and expounded on the significance of the seuda of Melave Malka instituted by Dovid HaMelech, and explained how his zechus protects and saves those who celebrate it.
To illustrate this, he related a story of two Yiddishe business partners who always made a point of escorting the Shabbos Queen with a fitting Melave Malka, even when doing so was exceedingly difficult. Once, the big regional fair was to take place on Sunday. Since they would have to begin their journey on Motzaei Shabbos, they packed food and planned to eat their Melave Malka on the way. As they traveled through the freezing night, a heavy snow began to hide the path they were following. Remembering that they had not yet eaten their Melave Malka, they decided to stop, but then realized that they had no water with which to wash their hands. Looking around, they noticed a light twinkling from afar. They traveled towards it and arrived at a little hut, apparently the home of a local peasant. They knocked on the door and asked if they could wash their hands. The stranger who opened the door invited them in to warm themselves and eat their meal, so the partners sat down for their seuda and sang in honor of the Shabbos Queen.
Suddenly, without warning, just as they were preparing to leave, a vicious gang of thugs appeared and blocked their way out.
"You won't leave here alive!" they shouted. "We kill whoever comes here and help ourselves to all their belongings."
There was no way out. The partners begged for a few minutes to say vidui, and the criminals granted them this last request.
At that moment, loud chimes announced the approach of a carriage, followed by knocks that made the door rattle. It was a poritz who had lost his way in the snowstorm and had come to ask for directions. His innocent request was greeted by raucous laughter. The robbers made it clear that he too would not leave their hut alive, and demanded that he hand over all his money. Having no choice, he obeyed, but made a last request – that he be given a little whiskey to quench his thirst. To this they agreed, and he invited them to join him. Just as they began to drink, they suddenly became paralyzed like stones, utterly unable to move. The poritz turned to the partners, and instructed them to pick up their belongings and escape. Within minutes, they were far from the danger zone. The Chortkover Rebbe concluded, "Do you know who the poritz was? It was Dovid HaMelech. He had come to save these partners in the zechus of their particular care to conduct their Melave Malka properly, including washing for the seuda."
The next morning two strangers arrived in Chortkov, and recounted the miracle that had occurred to them on their way to the fair...
(דברי דוד ליקוטים קפ"ט)
Many minhagim are associated with this seuda, all stemming from holy sources. Among them: Drinking or eating something hot, for Chazal refer to this as a remedy (and some say that it is a segula for feeling calm throughout the coming week); saying "da hi sudasa d'dovid malka meshicha” (this is the meal of Dovid King Moshiach); and telling stories of tzaddikim, particularly about the Baal Shem Tov, which is a segula for many things. It is known that the Rebbe observed the first two of these minhagim.
(ליקוט סעודת מלוה מלכה)
Consider
Why do we continue with our Shabbosdik food and clothing after Shabbos has ended?
At what point is Shabbos really gone: after havdala, after Melave Malka or later?
