Siman - Shabbos Daf 19
- Setting sail on a ship less than three days before Shabbos
It was taught in a Baraisa that one may not embark on a ship less than three days before Shabbos, unless it is for the purpose of a mitzvah.
-The Rif explains that the Rabbis prohibited such travel since a person typically feels seasick the first three days of travel and this would diminish one’s ability to enjoy Shabbos.
- In the case of travelling for the purposes of a mitzvah, the principle of העוסק במצוה פטור מן המצוה applies[O1] . (This means that one who is preoccupied with a mitzvah, is free from performing another mitzvah that would interfere with the first). Hence travelling to do a mitzvah would be permitted even though it will prevent him from performing the mitzvah of enjoying Shabbos.
- Giving clothes to a launderer before Shabbos
R’ Tzadok said it was the custom of Rabban Gamliel’s household to give white clothes to the launderer three days before Shabbos, but they would give colored clothes even on erev Shabbos. White clothing is harder to clean and therefore it takes more time for the cleaning to be complete before Shabbos begins, whereas colored clothing can be fully cleaned before Shabbos begins, even when given to a launderer on erev Shabbos.
Being that white clothes are harder to launder, the price to do so is higher. Abaye used this insight to challenge a launderer who wanted to charge him the same amount for colored clothes as he was charging for laundering white clothes.
- Roasting or baking erev Shabbos
The final Mishnah in the perek prohibits roasting meat, onions or eggs on erev Shabbos unless there is enough time for them to become roasted before Shabbos. Similarly, one may not place bread in the oven or a biscuit upon coals, close to the nightfall of Shabbos, unless there is enough time for it to crust while it is still day.
The concern in all of these cases is that if they are not sufficiently roasted or baked by the time Shabbos begins, one may come to stir the coals on Shabbos.
