[1] Beitza 16a. The Magid of Mezerich (Meor V’Shemesh, Shemos, in the Haftora to Shabbos and Rosh Chodesh) says that on Shabbos each one according to his level receives an additional נפש, רוח, and נשמה (three parts of the soul). Since one draws down Shabbos upon himself, he draws down an additional נפש, רוח, נשמה. The Sefer Aspaklaya Hamira (Yisro) writes that the additional נפש comes on Erev Shabbos after Chatzos—that is after one prepares himself for Shabbos. The extra רוח comes before ויכולו by Tefila when one says פורש סוכת שלום....  The added נשמה comes on Shabbos by Shacharis when one says נשמת.

[2] Shemos 31:17. The Divrei Shaul (died in 1885) writes (ח"א, Beitza 16) in regard to the נשמה יתירה that there are those who on Shabbos are able to eat abundantly while during the week they are מסתפק במועט, eat little. It was said about R’ Avraham Hakohen of Amsterdam that for 40 years, the entire week he would fast, and on Shabbos he would eat without limit, for the honor of Shabbos.

[3] The Mishna Brura (491:3) writes that there is no נשמה יתירה on Yom Tov. It is said in the name of the Magid of Mezerich that on Rosh Chodesh, one receives an additional נפש but not רוח and נשמה (Taamai HaMinhagim p. 127 s.v. ובספר. See Yesod Vshoresh Havoda in Shaar Hatzon 9:2).

[4] Shemos 31:17.

[5] For this reason, we smell בשמים by Havdala (Mishna Brura 491:3).

[6] To get an idea of who R’ Tzadok was, let us cite the words written before his Sefer Sichas Malachai Hasheras (s.v. ובן): The nephew of R’ Tzadok—R’ Moshe—was raised by R’ Tzadok from the age of 6 months. He related that he merited to hear personally from R’ Tzadok that at a year old he was able to talk and from then on, he said שהכל when he nursed. At age two, he davened all of davening from a Siddur prior to eating. At the young age of 3 ½ he learned Gemara and Tosafos. If that wasn’t enough, let us relate the unbelievable story that occurred when he was just 7 years of age in the year 1830. R’ Tzadok’s uncle who wrote a Sefer titled כפות זהב traveled to distant areas to raise money to print his Sefer. A half year passed and no one heard from him. Due to the pain his family endured as a result, it was revealed to R’ Tzadok from שמים where his uncle was and that he received a position as Av Beis Din. This calmed his family. Later it was verified that this is what happened.

[7] In the Sefer לבוש מכלול (Siman 4), the author writes that the Tzadik, the holy one, R’ Shimon of Yaaraslov would eat Melave Malka with others on Sunday afternoon. 

[8] Incidentally, let us cite the Chizkuni (to Shemos 16:23): We know that on Friday, they received a double portion of מן. This also included the meal for Motzai Shabbos—Melave Malka.

[9] Mishna Brura 300:2. The Gemara (Shabbos 119b) tells us חמין במוצאי שבת מלוגמא, hot water on Motzai Shabbos is a remedy. R’ Aryeh Leibush commented that this is a רפואה not to be sad. This is hinted to in ומחבש לעצבותם, the one who binds up their sorrows (Tehillim 147:3), as מחבש forms an acronym of חמין במוצאי שבת מלוגמא and לעצבותם refers to עצבות, sadness (Orchos Chaim, Siman 300). Parenthetically, the Zemiros of Melave Malka are uplifting as it speaks of the Geula and the like.

[10] Kaf Hachaim 300:1. The Elya Rabba writes that this limb is called לוז and a person is formed from it. When one dies, this bone doesn’t dissolve and if you put it into fire it won’t get burned.  If you put it into a mill, it won’t get ground nor will a hammer shatter it. From this bone, one will be revived by תחית המתים. Since Adam ate from the עץ הדעת and his limbs received pleasure from it, it was decreed that they would return to the עפר. However, the לוז is different since it receives no pleasure except from Motzai Shabbos. See Breishis Rabba 28:3.

[11] Breishis 28:19, 30:37. The first letters of ...ליעקב לאשה ותלד זלפה (Breishis 30:9-10) spell לוז. Likewise, the initials of למות ולמה זה (Breishis 25:32) form לוז, as this is the opposite of Esav.

[12] Taanis 5b.

[13] This fits well with the Gemara that relates that the angel of death has no permission to pass through לוז (Sota 46b).

[14] Breishis 35:14.

[15] A hint to Melave Malka is found in ויצא יעקב מבאר שבע... (Breishis 28:10-12). ויצא יעקב מבאר שבע—when a Jew departs from the well that is Shabbos, the 7^th. וילך חרנה—about to enter the place of חרון אף, turbulent waters, desires and temptations of the week. ויפגע במקום—he hits a wall where עולם הזה is like a stone wall blocking out Kedusha and clarity. ויחלום והנה סלם מצב ארצה—he saw a  ladder that had its feet in weekdays. וראשו מגיע השמימה—but its head was in Shabbos. That ladder is סלם—סעודת לויה מלכה as it connects Shabbos to the weekday.

[16] Shaar Hatziyon 300:7. Seudas Melava Malka is called the Seuda of Dovid Hamelech as we say by Melave Malka דא היא סעודתא דדוד מלכא משיחא because he established the yoke of Teshuva that even after one messes up, he is able to come close to Hashem (Pri Tzadik, Motzai Yom Kippur, 11). It has therefore been suggested that one can fix the sin of Adam specifically on Motzai Shabbos as this is when the light was removed because of his sin. He sinned with eating. Therefore, we can have proper intentions when we eat at Melave Malka, to fix up the sin. 

[17] Breishis 3:19.

[18] חסד לאברהם, מעין רביעי נהר נ"ב. Let us mention a story about this holy man. In about the year 1610, R’ Avraham and his family set out for Eretz Yisrael. After a stormy journey, the shaky ship finally docked at a port in Egypt. The passengers went ashore leaving their belongings on board. While on land, a strong storm wind blew the ship, anchor and all, out to sea where it sank with all of R’ Avraham’s possessions on board. Having escaped death, his signature from then on was in the form of a ship—in recognition of the miracle.