It is a principle of avodas Hashem to always be serene and calm, and one achieves this through emunah and bitachon. A person achieves serenity when he is happy with his lot and is always thanking Hashem both for what he has and for what he does not have – for someone who always focuses on what he is lacking and keeps running after more and more – his soul is not at peace, and he does not have menuchas hanefesh.
When a person knows that he is always in Hashem’s Hands, then he always feels like a baby in his mother’s arms. He does not have pressure or worries, and nothing agitates him. Through this, he succeeds much more, both in quantity and in quality.
In Parshas Beshalach (Shemos 15:25) we learn: “There He issued statutes and laws.” Rashi explains that in Marah, Hashem gave them some of the parshiyos of the Torah, specifically Shabbos, parah adumah, and other laws. The Sefer Hachinuch explains (mitzvah 24) the mitzvah of techum Shabbos: One of the aspects of Shabbos is for us to rest in one place just as Hashem, so to speak, rests on the seventh day.
In Marah, just after the sea split for them, Bnei Yisrael received the mitzvah of Shabbos, and we can find a connection between the two things: Water is always in motion, without any rest. Maharal (Gevuros Hashem ch. 18) explains that water is a substance that has no shape or form, and only someone who has separated himself from material desires and rules over them merits tzurah – form. Moshe Rabbenu is called Moshe for he was “pulled out of the waters” – he left behind the inherent trait of water, and he was zocheh to the greatest tzurah possible.
It is possible that because of this the Egyptians were punished specifically with water, in order to show that they chased after their desires, and they are compared to water, which has no rest and has no form. And thus, after Am Yisrael saw the Egyptians’ punishment at the Yam Suf, they were given the day of Shabbos, a day of rest and bitachon, a day of healing from the pursuit of one’s desires.
Excerpts from the popular shiur by Harav Yehuda Mandel shlit”a from Lakewood
