Rabbi Aba says that for one who observes the Sabbath, it is as though he observed the whole Torah, since the Sabbath is the delight of everything. One should invite the Sabbath in, like a guest. On the Sabbath secular speech is forbidden because it stimulates secular things above, and the Sabbath becomes blemished. When Pharaoh was coming to do battle with Yisrael, "Hashem shall fight for you, and you shall hold your peace;" this meant that the arousal took place from above - the children of Yisrael did not need to arouse anything from below.
Rabbi Yosi wonders why, if Hashem is always a connotation of Mercy, there seemed to be no mercy in the act of drowning the Egyptians. Rabbi Yehuda quotes Rabbi Shimon as saying that the Judgment had been tempered with Mercy since God had desired their honor that they be buried in the ground, and He had stretched out his hand so the earth would accept them. If Yisrael had aroused from below, Judgment would not have been executed with Mercy. Even though Hashem does Judgment, He is still compassionate for His creations.