Although the mitzva d'oraita is to thank God only when you are satiated from the meal, chazal decreed that we say birkat ha'mazon even when eating only the volume of a k'zayit and even if not satiated. So you must still say birkat ha'mazon after eating at least 1.3 fl. oz. (39 ml, or 1/6 cup) of bread within four minutes--even if you are not full.  This is known as birkat ha'mazon d'rabanan.

You make take medicines for any reason on d'rabanan Jewish festivals--even medicines not allowed on the first day of Jewish festivals--except:

• Medicines that you smear on skin.
• If the Jewish festival falls on Shabbat (which can only be second day of Shavuot).
  Note The d'rabanan Jewish festivals are the second day of Jewish festivals except Rosh Hashana (actually, the second day of Rosh Hashana IS d'rabanan but has the status of d'oraita), plus the last day of Passover and Sukkot outside of Eretz Yisrael.

You may directly instruct or ask a non-Jew to do melacha d'rabanan for you on Shabbat, but only:

• To prevent a large financial loss.
  Note A large loss is subjective to the individual's actual wealth and also to that person's perception of what is a large loss. Consult a rabbi.
• For Shabbat needs.
  Example You may ask a non-Jew to unlock an electric hotel door or trigger an entrance door on Shabbat, since this is for a Shabbat need and the action is not prohibited d'oraita.
  Situation A new guest arrives and you need the space on the table occupied by your Shabbat candlesticks.
  What To Do You may not move the candlesticks, but you may ask a non-Jew to do so.
  Situation You left a non-muktza item that you now need for Shabbat on a tree branch (or a child left one in a tree house!).
  What To Do You may not climb the tree to retrieve the item, but you may ask a non-Jew to retrieve it. Example You may ask a non-Jew to turn on air conditioning.
  ExampleYou may ask a non-Jew (directly, no need to hint) to turn off a light if it interferes with someone's sleeping.

  • To allow doing a mitzva.
  • For other pressing (and certainly for life-threatening) needs, such as health, even if the person not sick.

  Note All of these are d'rabanan cases!

Issues of boreir are almost always d'oraita, not d'rabanan, and therefore we are stringent in applying restrictions concerning boreir.
Unlike on Shabbat (when you must remove some good along with the bad so as not to violate the melacha of boreir), on Jewish festivals you may remove the bad from the good if it is easier to take the undesired food from the desired food.

You may select desired food from undesired (or inedible) substances if you follow these two rules:

• Food from other food, or
• Food from other substances.
  Note You may remove dirt from a carrot's surface by scraping the peel with a knife (a tool not specialized for separating food), but not by using a peeler.
  Exception As on Shabbat, an action necessary to eat a food normally (derech achila) does not violate the prohibition of boreir. So you may peel a food that is normally separated from its peel or shell in order to be eaten, as long as you do not use a specialized instrument to do so.

• You may peel an orange by hand, with or without a knife.
• You may remove the shells from peanuts by hand.
• You may remove the shell from a hard-boiled egg by hand.

• Remove fish bones from fish while you are eating the fish or just before eating it.
• Cut open a melon such as a cantaloupe and remove any seeds normally.

Three Shabbat Meals
We are required to eat three Shabbat meals, as a rabbinic (d'rabanan) enactment to enjoy Shabbat (oneg Shabbat). The first Shabbat meal must be at night and the remaining two must be during the day (the third meal must be eaten after halachic midday). Friday night dinner and the first meal on Saturday are preceded by kiddush. For the first two Shabbat meals, say ha'motzi over two complete loaves of bread, each of which is at least 1.3 fl. oz. in volume. For the third meal, the ideal is to use two complete loaves of bread, but the requirement of eating the third meal can also be fulfilled by eating any food other than salt or water.

Source of Saying Shabbat Kiddush

• Saying kiddush on Shabbat night is a commandment from the Torah (d'oraita).
• Saying kiddush on Saturday morning is a rabbinical (d'rabanan) enactment.

Note If you did not say Friday night kiddush, you must say that version of kiddush on Shabbat morning and it is then a requirement from the Torah (d'oraita). Do not begin with va'yechulu; instead, begin with borei pri ha'gafen and say the second blessing of kiddush.

Source of Kiddush Location
Saying kiddush at the place where you will eat your meal is a rabbinical (d'rabanan) enactment.

Shabbat Kiddush-Meal Quantities: Evening

• For evening kiddush, a minimum of 4 fl. oz. (119 ml) of wine must be blessed on and at least half must be drunk.
• For the evening meal, as on Shabbat lunch and all required Jewish festival meals, a minimum of 1.9 fl. oz. of bread must be eaten within four minutes.

Shabbat Kiddush-Meal Quantities: First Meal on Saturday
Shabbat day first meal has two separate eating requirements.  They may be combined (say/hear kiddush and start the main meal right away) but are often done separately (say/hear kiddush and then eat some mezonot; the main meal is eaten later in the day).
Note Since eating and drinking requirements on all morning kiddushes (both Shabbat and Jewish festivals) are d'rabanan, the required beverage amount for morning kiddush is only 3.3 fl. oz. (99 ml) instead of the d'oraita 4 fl. oz. (119 ml), which is required for kiddushes for Shabbat evening.
1) Morning kiddush requires a halachically legal “meal” with these elements:
      a) Blessing on a minimum of 3.3 fl. oz. (99 ml) of wine (or other beverage),
      b) Someone's drinking at least 2 fl. oz. of the beverage, followed by
      c) Eating at least 1.3 fl. oz. (39 ml, or 1/6 cup) of some type of mezonot (or bread) within four minutes.
Note If you drink at least 3.3 fl. oz. (99 ml) of wine within 30 seconds, you do not need to eat mezonot.
Note You do not need to drink the wine or other kiddush beverage to fulfill “establishing a meal.” You may hear kiddush and then simply eat the required amount of bread or mezonot. This applies to Shabbat or Jewish festivals, evening or morning.
The kiddush “meal” does not have to satiate.
Note If you have not fulfilled the requirements for kiddush, you may not eat other foods, such as fruit or fish at a kiddush.

2) The real meal (kovei'a se'uda) of Shabbat lunch requires eating at least 1.9 fl. oz. (56 ml) of bread (or matza during Passover!) within four minutes. It should include enough food to satiate.
Note You can simultaneously fulfill the requirement to “establish a meal” and to “eat a meal” by eating one (the same) piece of bread.
For details on fulfilling the first two meals' requirements, see Shabbat: Kiddush.

Shabbat: Eating a Meal Requirement: Third Meal
For details on fulfilling the third meal's requirements, see Shabbat: Third Meal (Se'uda Shlishit).

If you fly through Shabbat (permitted for business only), you must keep even Shabbat d'rabanan while flying over the area of the earth that is in Shabbat.
If you fly east (such as from Asia to the US, across the Pacific) after Shabbat is over, you will re-enter Shabbat and may not do melacha on the airplane. Say the Shabbat prayers and kiddush at the appropriate local time where you are flying.
 

Although human dignity (kavod ha'briot) cannot override Torah commandments, kavod ha'briot allows violating some d'rabanan laws in order to avoid embarrassment.
Examples

• Tearing Toilet Paper
  Situation You need to use toilet paper on Shabbat but none is torn.
  What To Do You may tear some toilet paper using any non-standard method or change from the normal way (shinu'i), such as not using your hand, or dropping something on the paper.
• Hearing Aid
  Situation You may speak to someone who uses a hearing aid on Shabbat to avoid embarrassing him or her.

Shalom bayit is a family at peace, as one unit. When leniencies in law are used to avoid intrafamily conflicts, customs and d'rabanan halachot can sometimes be overridden. But d'oraita halachot may not be violated. Consult a rabbi.
Situation
You want to go to minyan but your wife is overwhelmed with trying to feed several children and she asks you to help.
What To Do
You must miss minyan and help her since your wife's needs take precedence over your wish to pray with a minyan.
Note With shalom bayit problems between spouses, a rabbi should be consulted for details.
Note Once someone is married, his or her in-laws are part of his or her family and are included in shalom bayit rules.

An oven that has not been used for at least 24 hours is considered, d'oraita, to be neutral/pareve, but only if it is clean. D'rabanan, it is still not kosher, but this may be useful for when you can be lenient; e.g., if there is a safek.

Try to say 100 blessings a day.  This is easy on weekdays since Ashkenazim say about 89 blessings just in the prayer services.
NoteSaying 100 blessings each day is a halacha drabanan.

You may talk about weekday subjects on Jewish festivals if what you are discussing already happened, but you may not discuss plans to do activities that involve any type of melacha, even d'rabanan.

BAKING IN NON-KOSHER OVEN

An oven that has not been used for at least 24 hours is considered, d'oraita, to be neutral/pareve, but only if it is clean. D'rabanan, it is still not kosher, but this may be useful for when you can be lenient; e.g., if there is a safek.

Note Even when baking in a non-kosher oven, you must cook the food in a kosher utensil.

INTRODUCTION TO BAKING IN NON-KOSHER OVEN

Baking in a Non-Kosher Oven

How To Tell if Oven Is Clean

To determine whether a non-kosher oven with black or brown spots is clean, scratch them:

• If the substance crumbles, the spots are OK and you may bake non-liquid food in that oven without covering the food.
• If the spots do not crumble or they remain immovable or come off in flakes rather than crumbles, consider the oven not clean.

Uncovered Food; Clean (Non-Kosher) Oven

You may cook food uncovered in a non-kosher oven if:

• The oven rack and walls are clean, and
• The food is not “liquid.”
  
  Note Non-liquid is defined as not being liquid before cooking OR not being liquid after cooking, but the food does not need to be non-liquid at both times.  Examples of “non-liquid” foods:

  • Apple cobbler
  • Lasagna
  • Meat (that will create gravy at the end)
  • Pudding
  • Raw fish.

What To DoPlace two layers of foil under the baking utensil.

Double Wrapping

When To Double Wrap

Double-wrap food before baking in a non-kosher radiant-heat oven if:

• The rack and/or oven are not clean;
• The food that you are baking is liquid at any time during the cooking process; OR
• Some of the food you are baking spills onto the rack or oven surfaces.

How To Double Wrap

When wrapping food for cooking in a non-kosher oven, the wrapping material does not need to seal completely, but the:

• Food must be completely covered with two layers of foil or plastic;
• Layers must keep water vapor out from between the layers; and
• Surfaces of the utensil must all be covered.

Jewish Festivals: Medicines: When To Take
Medicine generally may not be used on the d'oraita Jewish festival days.

Jewish Festivals: Medicine for Chronic Diseases
You may take medicine on Jewish festivals (whether d'oraita or d'rabanan) for:

• Chronic diseases, such as Parkinson's disease, or
• Any disease that affects your entire body.

Jewish Festivals: Medicine for Non-Chronic Diseases
You may take medicine on Jewish festivals for non-chronic illnesses, if skipping one day will prevent cure.  You may not take medicine for non-chronic illnesses if skipping a day will just delay your being cured (unless the disease affects your entire body--in which case, you may take the medicine).

Jewish Festivals: Medicines: When To Take: D'Oraita Festival Days
Here are the d'oraita Jewish festivals:

• First day of Sukkot, Passover, and Shavuot
• Seventh day of Passover
• Shmini Atzeret (8^th day of Sukkot)
• Yom Kippur
• Both days of Rosh Hashana (even though the second day is d'rabanan).

On these days, as well as on d'rabanan Jewish festivals, you:

• MUST take medicine whenever there is any question of a life-threatening disease or condition.
• MAY take medicine for a condition that affects the entire body (illness, weakness, etc.). Consult a rabbi if possible.
  ExceptionYou may not smear substances on skin UNLESS the illness is life-threatening, in which case even smearing is permitted.
• MAY use some medicines if only part of your body is affected by a non-life-threatening disease--consult a rabbi.

Jewish Festivals: Medicines: When To Take: D'Rabanan Festival Days
You make take medicines for any reason on d'rabanan Jewish festivals--even medicines not allowed on the first day of Jewish festivals--except:

• Medicines that you smear on skin.
• If the Jewish festival falls on Shabbat (which can only be second day of Shavuot).

A hot (120° F--49° C--or more), wet utensil transfers its gender to a countertop upon which it is placed, but only at the area of contact.
Status of Countertop

1. Gender status of the countertop:
   • D'rabanan, the countertop area of contact remains that gender until kashered (as long as the countertop material is kasherable).
   • D'oraita, the countertop reverts to kosher-neutral/pareve after 24 hours.
   Note If the utensil and counter were not wet (nor dirty with food) at the area of contact, there is b'di'avad no transfer of gender.
2. If you put a hot, wet utensil of the opposite gender on that same spot, that counter space may become non-kosher.

Status of Utensils
If the counter had not had a hot, wet utensil/container of food of the opposite gender placed on the same spot within 24 hours of each other, the utensils may be used and the utensils are still kosher.
Status of Food
This does not apply to food that is directly placed on the counter, in which case the food might become non-kosher.