Why do we say Havdala in the blessing of Atah Chonen? The Yerushalmi in Brachot says, “Im ein da’at havdala minayin.” Without intellect, it is impossible to distinguish between different things. To make Havdala, one needs a measure of intellect. On Shabbat we are focused solely on spirituality. We don’t ask for any physical needs. Havdala serves as a sanction to begin working again. Therefore, Ata Chonantanu is inserted before the first supplication of mercy in order to allow us to engage in further requests.
If you forget Ata Chonantanu, you don’t have to recite it again, if you will be reciting Havdala over wine. If you didn’t say either of them, you must recite the prayer in Shachrit. The Mishna Berura cites the Magen Avraham that the makeup prayer would be the second prayer. Rav Akiva Eiger disagrees. Ata Chonantanu should be inserted in the first prayer because one needs its sanction to engage in further supplications.
One should not eat, drink, or do work before Havdala. If you are in the middle of a bread meal that you started before the end of Shabbat you can continue eating without reciting Havdala, but if it is just a fruit or cake meal, you must stop before bein hashmoshot, thirty minutes before the stars appear. Once Shabbat ends, one should say ‘Baruch hamavdil bein kodesh l’chol’ and then work is permitted. Women who generally don’t daven Maariv should be careful to say this. Why can’t we eat or do work before Havdala? On some level it’s still Shabbat, until it is formally concluded. In addition, Chazal wanted to be sure we wouldn’t forget to make Havdala.
The cup for Havdala must not be pagum (flawed). It is filled until the wine overflows, showing our confidence in Hashem’s beneficence.
The Mishna Berura mentions that women shouldn’t drink the wine because it is possible that they are not obligated in the blessing over the flame and there’s a hefsek (break) between Hagafen and the drinking.
Many poskim maintain that one cannot fulfill Havdalah over the phone. Rav Moshe ruled that where there is no choice, it is permitted.
We smell sweet smelling spices to give us a lift after losing our neshama yeteirah, (extra soul). According to the Mishna Berura, one should not make a blessing on the spices if one can’t smell.
One should use an avuka, a candle with multiple wicks for the blessing on the flame. Most poskim do not consider electricity to be aish (fire), but some rule that an incandescent bulb does fall under this category.
There is a custom to escort the Shabbat out with a bread meal, called Melave Malka. One should eat as soon after Shabbat as possible so that it’s noticeable that it’s not just a regular meal. If one is very full then one should at least eat fruit or mezonot. Our sages tell us that the luz bone is nourished with the food of Melave Malka. The resurrection of the dead will begin from this bone. Melave Malka highlights the sanctity of Shabbat. Shabbat is not just a one day affair. It’s a reservoir of holiness that flows over into the coming week.