וביום השביעי שבת וינפש (תפילה בלחש בשבת)
The Gemara (Beitzah 16a) states that HaShem provides an extra soul to each Jew at the beginning of Shabbos, and at the conclusion of Shabbos He takes it away, as the verse says וביום השביעי שבת וינפש which hints at “woe that we lost a soul” (וי אבדה נפש) since Shabbos ends.
The Halacha (O.C. 296) says that it preferable to use wine for Havdalah rather than any other beverage. Even if “pagum” (previously drank from) wine is available one should use it rather than another beverage. However, the reason is not given. Possibly, due to the bitterness of the soul from the loss of the pleasure of the additional soul one needs wine to offer comfort. Similarly, we use spices at Havdalah to ease the pain of the loss of the extra soul.
In addition, the word שביתה implies a cessation from major issues, whereas נופש indicates cessation from only “lighter” issues. For example, regarding a Ger Toshev (a non-Jew that accepted the to keep the 7 mitzvos and thus, has permission to remain in Eretz Yisrael) is permitted on Shabbos to do actions like those that a Jew would be permitted to do on Yom Tov, for needs of food (a “lighter” set of cessation. This difference is reflected in the verse about the cessation of a Ger (Shmos 23, 12) ונפש (and not the word וישבות) which indicates the “lighter” level of cessation.
