905. When We May and May Not Cry Out on Shabbos

Shabbos 30:12

We may not fast, cry out to God, or in other ways beg His mercy on Shabbos. Even if a community is undergoing crises that would otherwise require fasting and blowing shofar, we do not fast or blow shofar on Shabbos or yom tov. However, if a city is under siege or being flooded, or if a ship at sea is sinking, we do blow shofar on Shabbos in order to summon help, we cry out on their behalf and beg mercy for them.

Shabbos 30:13

We do not begin a siege on enemy cities fewer than three days before Shabbos. This is so the soldiers’ minds should not be agitated on Shabbos. Similarly, we do not set sail on a ship fewer than three days before Shabbos so that passengers’ minds will be settled before Shabbos and they will not suffer unnecessary discomfort. It is permitted, however, to depart on a sea voyage even on Friday when traveling for the sake of a mitzvah. One should make an agreement that the ship will not continue sailing on Shabbos but if the captain and crew do not honor the agreement, it is of no consequence. A short voyage, such as from Tyre to Sidon, may be made on Friday even on matters of personal business. In places where the accepted practice is not to set out on a journey on Friday, one may not do so.