(18:1) Jethro, the minister of Midian, the father-in-law of Moses, heard everything that God did to Moses and to Israel, His people—that God had taken Israel out of Egypt.
Jethro heard What news did he hear that prompted him to come and convert? R. Yehoshua says: He heard of the war with Amalek, because the present verse is preceded by “Joshua weakened Amalek and his people with the sword's blade” (17:13). R. Elazar Hamoda'i says: He came because he heard of the giving of the Torah, and this inspired him to convert. For when God gave the Torah to the people of Israel, the sound carried from one end of the world to the other.
R. Eliezer said: He heard of the parting of the sea, and that prompted him to come. For it says “It happened that when all the kings of the Amorites heard … that God had dried up the Jordan's waters …” (Joshua 5:1). Because the term heard in this verse refers to the drying up of the Jordan's water, it has a similar connotation when it is used in the present verse in connection with Jethro; he heard of the parting of the sea (Zevachim 116a).
(18:4) The name of the other son was Eliezer, for Moses said, “My father's God—Eli—was my helper[ezer],and He saved me from the sword of Pharaoh.”