Finding the Afikoman - Clue #4

You found it!

Why do you think that we end our Passover seder with this wish?

לְשָׁנָה הַבָּאָה בִּירוּשָלָיִם הַבְּנוּיָה.
Next year, let us be in the built Jerusalem!

Clue #4

Which blessing, said before the meal, has an additional paragraph if the seder is on a Saturday night? Find the extra paragraph.