Question: Upon the conclusion of the Shabbat night meal, may one immediately wash the dishes for the Shabbat day meal or should this only be done during the day closer to the start of the meal? Also, is it permissible to pour water onto soiled dishes (which one no longer needs for Shabbat) so that it will be easier to wash them after Shabbat?
Answer: In the previous Halacha we have discusses the law that one may not wash dishes on Shabbat when they are not necessary for the day of Shabbat itself. The source of this law is that one may not prepare for a weekday on Shabbat. The reason for this prohibition is because one may not toil on Shabbat for something which is not necessary for the actual day of Shabbat.
Regarding the first question mentioned above, the Talmud Yerushalmi (Shabbat, end of Chapter 15) states: “Glasses and bowls may be washed on Shabbat night for the day meal.” It seems form the words of the Yerushalmi that one may do so immediately on Shabbat night following the Shabbat night meal. The Olat Shabbat, Eliyah Rabba, and others rule likewise. Maran Rabbeinu Ovadia Yosef zt”l rules likewise as well.
Regarding the second question, it would seem that it should be prohibited to do so, for by pouring the water onto the soiled dishes, one is preparing for a weekday on Shabbat. Nevertheless, Maran zt”l writes that it seems that merely washing the dishes with water without actually scrubbing them is not considered toiling at all and our Sages only prohibited washing which entails toil; however, merely washing dishes with some water does not seem to fall into the category of forbidden dishwashing. He therefore writes that it is permissible to pour some water into a pot which has some food residue stuck to it so that it will not be very difficult to clean it on Motza’ei Shabbat.
Summary: One may wash dishes immediately following the Shabbat night meal, for as long as this is being done for the purpose of Shabbat, this is permissible.
One may pour water onto soiled pots and dishes so that food residue does not stick to them. Although one is doing so in order for the dishes to be washed more easily on Motza’ei Shabbat, this is nevertheless permissible.