שמות פרק יב, טז וּבַיּוֹם הָּרִ אשוֹן מִקְרָּא-קֹדֶׂש וּבַיּוֹם הַשְבִיעִי מִקְרָּא-קֹדֶׂש יִהְיֶׂה לָּכֶׂם כָּל-מְלָּאכָּה לֹא-יֵעָּשֶׂה בָּהֶׂם אַךְ אֲשֶׂר יֵאָּכֵל לְכָּל-נֶׂפֶׂש הוּא לְבַדּוֹ יֵעָּשֶׂה לָּכֶׂם:
On Yom Tov, all melacha מלאכה is forbidden with the exception of “ochel nefesh” (food preparation). However, only by this verse concerning the 7th day of Pesach is this exception stated explicitly.
On the 7th day of Pesach the miracle of the splitting of the Yam Suf occurred. And Chaza”l (Pesachim 118a) say קשים מזונותיו של אדם כקריעת ים סוף (a person’s livelihood is as difficult as the splitting of the Sea). Thus, the concept that G-d provides food (livelihood) occurs despite the difficulties, is reflected specifically that on the 7th day of Pesach (Splitting of the Sea) is noted the exception of food preparation on G-d’s Holy Day.
