"And Moshe told his father-in-law all that Hashem had done to Pharaoh and to Egypt for Israel's sake, all the hardships that had befallen them on the way, and how Hashem had saved them." (Shemot 18:7)
One might ask: what need did Moshe have to tell Yitro all this if he had already heard the facts? For it is written: "And Yitro heard... all that Hashem had done," and Rashi explains that he heard about the splitting of the Red Sea and the war against Amalek. What, then, did Moshe add with his account?
Furthermore, the Zera Berach asks: if it was already said that Yitro heard all that Hashem had done, why does the verse explicitly add "that Hashem brought Israel out of Egypt"?
Moreover, Rashi comments that the exodus from Egypt was "greater than all" the other miracles, which seems difficult to understand, as the splitting of the Red Sea — which extraordinarily altered the order of nature — would seem to be an even greater miracle.
The explanation is as follows: Yitro, having been a priest of idolatry and a great sorcerer, believed that sorcery had the power to oppose — Hashem forbid — the heavenly forces. Therefore, in his eyes, the miracle of the Shemot from Egypt was the greatest of all, even greater than the splitting of the sea. This is because Egypt was "sealed" by means of sorcery, so that no slave could escape from there. Therefore, although Yitro heard of all the miracles, the fact that Hashem brought Israel out of Egypt impressed him in a special way: he saw that the power of HaKadosh Barukh Hu was superior even to sorcery. For this reason, he came and converted.
Moshe perceived that, even having heard about the splitting of the sea and the war against Amalek, Yitro had been primarily impressed by the exodus because in it the forces of impurity and sorcery were nullified. Understanding that Yitro did not know that these same forces were also nullified in the splitting of the sea and in the war against Amalek, Moshe explained it to him: at the Red Sea, the Divine power was so great that even the angel of Egypt (spiritual dominion) was surrendered and drowned in the sea, as the Zohar teaches; and in the war against Amalek, whose power resided mainly in sorcery, Hashem defeated them and nullified them completely, as Rabbenu Bahya explains.
(Zera Shimshon, Parashat Yitro, Art. 3)
