"Smite a scorner, and the simple will beware." The destruction of Amalek brought Jethro to his senses. Jethro was originally in the same plot with Amalek, both having incited Pharaoh against Israel, but when he saw that Amalek lost this world and the other, he repented of his sinful ways, saying: "There is nothing left to me but to go over to the God of Israel";  and although he dwelt in the greatest wealth and honor, he determined to set out for the desert, to Moses and his God.  Arrived at the camp of Israel, he could not enter it, for it was enveloped by a cloud that none could pierce, hence he wrote a letter to Moses and shot it off with an arrow, so that it fell into the camp.  The letter read: "I adjure thee, by thy two sons and by thy God, to come to meet me and receive me kindly. If thou wilt not do if for my sake, do it for thy wife's sake; and if thou wilt not do it for her sake, do it for thy sons' sake." For Jethro brought with him his daughter Zipporah, from whom Moses had been divorced, as well as her two sons, her only children, for after her separation from Moses, she had wed no other man.
At first Moses was inclined to give no ear to this letter, but God said to him: "I, through whose word the world came into being, I bring men to Me and do not thrust them back. I permitted Jethro to approach Me, and did not push him from Me. So do thou, too, receive this man, who desires to betake himself under the wings of the Shekinah, let him approach, and do not repulse him." God herewith taught Moses that one should repulse with the left hand, and beckon with the right. 
Moses, Aaron, Nadab, and Abihu, together with the seventy elders of Israel, carrying with them the sacred Ark, hastened to welcome Jethro kindly; and Moses so honored his father-in-law as to make an obeisance before him and kiss him. Before Moses told his father-in-law of the great miracles God had wrought for Egypt, such as the exodus from Egypt, the cleaving of the sea, the rain of manna, and the rest, he offered him the greeting of peace; for great is peace, that precedes event he praise of God.  After the peace-greeting, Moses, to draw his father-in-law nearer to true faith in God and His revelation, began to relate to him the miracles that God had wrought for them at the exodus from Egypt, during the passing through the Red Sea, and during the war with Amalek. He said, moreover, "In the manna that God gives us we perceive the taste of bread, of meat, of fish, in short, of all the dishes there are. Out of the well that God gives us we draw a drink that possesses the taste of old wine as well as new, of milk and of honey, in short, of all the beverages that exist." "We shall," Moses continued, "receive six other gifts from God, the land of Israel, the future world, the new world, the sovereignty of David, the institution of priests, and of Levites."
When Jethro heard all this, he determined to become a Jew and to believe in the only God, and although he felt a pang at heart upon hearing that the Egyptians had perished - for no one should scoff at a heathen before a proselyte who is not a Jew of ten generation's standing - still he burst into a song of praise to God for the deeds He had one for His people. In truth, it reflects shame upon Moses and the sixty myriads of Jews that they had not given thanks to God for the release from Egypt, until Jethro came and did so. He said: "Praised be God who delivered Moses and Aaron, as well as the whole nation of Israel, from the bondage of Pharaoh, that great dragon, and of the Egyptians. Truly, great is the Lord before all gods, for whereas formerly not a single slave succeeded in escaping from Egypt, He led sixty myriads out of Egypt. There is no god whom I had not, at some time in my life, worshipped, but not I must admit that none is like the God of Israel. This God had not been unbeknown to me heretofore, but now I know Him better, for His fame will sound throughout the world, because He visited upon the Egyptians exactly what they had planned to undertake against Israel. They wanted to destroy Israel by water, and by water were they destroyed." 
With sacrifices and a feast was the arrival of Jethro celebrated, for after he had made the burnt offering not far from the bush of thorns that had been unscathed by fire, Jethro prepared a feast of rejoicing for the whole people,  at which Moses did not consider it below the dignity to wait on the guests in person. In this he followed the example of Abraham, who in person waited on the three angels, though they appeared in the guise of idolatrous Arabs.
Abraham like Moses sought to follow in the ways of the Lord, to provide each according to his wants, and to grant to everybody what he lacks, whether he be a righteous man, or an idolater, who through his sins conjures up God's wrath. 
To this feast the people sat down according to their tribes. They ate, drank and were merry, while Aaron and Jethro with their relatives sang songs of thanksgiving to God, and praised Him as the Creator and Donor of their lives and their liberty. At the same time they gave due appreciation to Moses, through whose courage everything had happily come to pass. In his words of gratitude to Moses, Jethro also gave expression to many glorious eulogies on the people of Israel, but he especially extolled Moses, who through difficulties and dangers had shown so much courage in the salvation of his friends.