"And Jethro heard" (Exodus 18:1). What report did he hear that he came? Rabbi Yehoshua says: He heard of the war with Amalek and came, for it is written right beside it (Exodus 17:13): "And Joshua weakened Amalek." Rabbi Elazar of Modi'in says: He heard of the giving of the Torah and came. For we find that on the day the Torah was given to Israel, all the kings of the earth trembled in their palaces, as it is said (Psalms 29:9): "And in His palace all say, 'Glory.'" All the nations of the world gathered before Balaam and said to him: It seems that the Holy One is destroying His world with water, as He destroyed the generation of the Flood, as it is said (Psalms 29:10): "The LORD sat enthroned at the Flood." He said to them: Fools, He has already sworn that He will not bring a flood upon the world, as it is said (Isaiah 54:9): "For this is to Me like the waters of Noah, when I swore that the waters of Noah should no more pass over the earth." They said to him: Surely a flood of water He will not bring, but a flood of fire He will bring. He said to them: He will bring neither a flood of water nor of fire; He is giving Torah to His people and bestowing reward upon those who fear Him. When they heard this from him, they all turned, each one to his place.
Rabbi Eliezer says: He heard of the splitting of the Sea of Reeds and came, for we find that on the day the sea was split for Israel, they heard it from one end of the world to the other, as it is said (Joshua 5:1): "And it came to pass, when all the kings of the Amorites who were beyond the Jordan westward, and all the kings of the Canaanites who were by the sea, heard that the LORD had dried up the waters of the Jordan before the children of Israel until they had crossed over." And so Rahab says to Joshua's messengers (Joshua 2:10): "For we have heard how the LORD dried up the waters of the Sea of Reeds before you." They said: She was ten years old when Israel left Egypt. All forty years that Israel was in the wilderness she was a harlot. At fifty years she converted. She said: With three things I sinned; with three things may He forgive me - with the rope, with the window, and with the booth, as it is said: "And she let them down by a rope through the window" (Joshua 2:15), and "she hid them with the stalks of flax" (Joshua 2:6).
"Jethro" (Exodus 18:1). At first they called him Jether, as it is said (Exodus 4:18): "And Moses went and returned to Jether his father-in-law." Once he performed worthy deeds they added one letter to him and he was called Jethro. So too you find with Abraham: at first they called him Abram; once he performed worthy deeds they added one letter to him and he was called Abraham. So too you find with Sarah: at first they called her Sarai; once she performed worthy deeds they added one letter to her and she was called Sarah for all the world. So too you find with Joshua: at first they called him Hoshea, and once he performed worthy deeds they added one letter to him and he was called Joshua.
Another interpretation: that a letter is withheld from them. You may learn from Ephron: at first they called him Ephron; once he set a price with our father Abraham and said to him, "a land worth four hundred shekels of silver, what is that between me and you?" (Genesis 23:15), they withheld one letter from him and he was called Ephran. So too you find with Jehonadab: at first they called him Jehonadab (2 Kings 10:15), and once he joined himself to the wicked one, who is Jehu, they withheld one letter from him and he was called Jonadab (Jeremiah 35:6). From here they said: Do not join yourself to a wicked man, even to bring him near to the Torah. So too you find with Ahab son of Kolaiah: at first they called him Ahab (Jeremiah 29:21); once he performed wicked deeds they withheld one letter from him and he was called Achav.
Seven names were given to Jethro: Jether, Jethro, Hobab, son of Reuel, Putiel, Keni. Jether, because he caused one extra section to be added to the Torah; the Holy One, blessed be He, gave him a section to take pride in. And which is it? The appointing of elders, as it is said (Exodus 18:21): "And you shall provide out of all the people." Jethro, because he performed worthy deeds. Hobab, because he was beloved to the Omnipresent. "Son," because he was like a son to the Omnipresent. Reuel, because he was a friend to the Omnipresent. And so it says (Exodus 18:12): "And Aaron came, and all the elders of Israel, to eat bread with Moses' father-in-law before God." Putiel, because he renounced every form of idolatry in the world. Keni, because he acquired the world to come.
"Priest of Midian" (Exodus 18:1). Rabbi Yehoshua says: He was a pagan priest, as in the matter that is said (Judges 18:30): "And Jonathan son of Gershom son of Manasseh, he and his sons, were priests to the tribe of the Danites." Rabbi Elazar of Modi'in says: He was a prince, as in the matter that is said (2 Samuel 8:18): "And the sons of David were priests." "Father-in-law of Moses." At first Moses honored him, as it is said (Exodus 4:18): "And he returned to Jether his father-in-law." Now his father-in-law began to honor him; they said to him: What is your distinction? He said to them: I am the father-in-law of Moses.
"All that God had done for Moses and for Israel" (Exodus 18:1) - Moses is weighed as equal to Israel, and Israel as equal to Moses; the teacher is weighed against the disciple, and the disciple against the leader. "For the LORD had brought Israel out of Egypt" - from here you learn that the exodus from Egypt is weighed before the Omnipresent against all the miracles and mighty acts that the Omnipresent performed for Israel.