מדרש על שמות 18:9

(Exod. 18:1:) NOW JETHRO PRIEST OF MIDIAN, <…>, HEARD. He was a priest for idolatry.¹⁷Mekhilta de Rabbi Ishmael, Amaleq, 3. (Exod. 18:9:) AND JETHRO REJOICED (rt.: YHD), in that he professed (YHD) the name of the Holy One. Another interpretation (of Exod. 18:9:) AND JETHRO REJOICED (rt.: YHD). <It was> that he became a Jew (rt.: YHD). (Vs. 10:) SO JETHRO SAID: BLESSED BE THE LORD. Jethro said: I did not leave a deity alone without serving him, but I have found no deity like the God of Israel. (Vs. 11:) NOW I KNOW THE LORD IS GREATER THAN ALL GODS. Four children of Adam said four things. If someone else had said them, they would have laughed at them.¹⁸Eccl. R. 3:11:1. And who were they? Moses, Jethro, Solomon, and Nebuchadnezzar. Moses said (in Deut 32:4): THE ROCK!—HIS WORK IS PERFECT, [BECAUSE ALL HIS WAYS ARE JUSTICE]. [If someone else had said it, they would have laughed at him, saying: From where does this one know the ways of the Holy One? However,] because it is written (in Ps. 103:7): HE MADE HIS WAYS KNOWN TO MOSES, it is therefore stated (in Deut. 32:4): THE ROCK!—HIS WORK IS PERFECT, BECAUSE ALL HIS WAYS ARE JUSTICE. Then Solomon said (in Eccl. 3:11): HE HAS MADE EVERYTHING BEAUTIFUL IN ITS TIME. If someone else had said it, they would have laughed at him, saying: Who has made known to this one what is beautiful and what is not beautiful? But, <in the case of> Solomon, whose table lacked nothing, he knew what was beautiful. R. Jose bar Hanina said: Solomon's table did not even lack bitter herbs¹⁹Tanh., Exod. 5:7, and Codex Vaticanus Ebr. 34 read “ice” here. of Tammuz nor melopepones {i.e., radish and lettuce}²⁰The Greek word means “melons.” of Tishri. Nebuchadnezzar said (in Dan. 4:32 [35]): ALL THE INHABITANTS OF THE EARTH ARE OF NO ACCOUNT. If another had said it, they would have laughed at him: Over what does this man rule? He does not even rule over a gnat. But in the case of Nebuchadnezzar it was fitting for him to say so, since it is stated concerning him (in Dan. 2:38): AND [INTO YOUR HAND HE HAS GIVEN] THE CHILDREN OF ADAM, [THE WILD BEASTS OF THE FIELD, AND THE FOWL OF HEAVEN,] WHEREVER THEY MAY DWELL; [AND HE HAS HAD YOU RULE OVER ALL OF THEM]. Jethro said (in Exod. 18:11): NOW I KNOW THE LORD IS GREATER THAN ALL GODS, because among all his gods he did not see one as great as the Lord. (Ibid., cont.:) YES, BY THE THING WHICH <THE EGYPTIANS> PLOTTED AGAINST THEM.²¹PRK 11:5. R. Eleazar said: By that with which the Egyptians intended to destroy Israel, <i.e.,> by water, by that they were destroyed. So they were drowned in the midst of the sea.

And Jethro rejoiced (Exod. 18:9). Do not read this word as vayihad (“and he rejoiced”) but rather vayihed (“and he became a yehudi [a Jew]”). Why did Jethro say: Blessed be the Lord (Exod. 18:10)? Jethro said: I have not neglected to worship any idol in this world, but I have found no god like the God of Israel. Now I know that the Lord is greater than all the gods (ibid. 11).