Yisro, Moshe's father-in-law, brought Moshe's wife and two children to him in the wilderness, where Bnei Yisroel were encamped at the mountain of Elokim. Yisro sent word to Moshe, “I, your father-in-law Yisro, am coming to you, and your wife and her two sons.” (Shemos 18,5-6)
Rashi explains the second possuk; I, your father-in-law, Yisro etc.: Even if you feel that I am undeserving for you to come and greet me, you should greet us because of your wife. If you believe that your wife is also not worthy, then you should come and greet us in merit of your two children.
Zera Shimshon asks, what made Yisro think that he was less deserving to be greeted than his daughter Tziporah? What flaw did Yisro see in himself that he felt a cause for this coldness? Also, what flaw did Yisro see in Tziporah that made him feel that Moshe would not come to greet and welcome her? Zera Shimshon explains in light of the Gemara in Yevamos 24b): in the days of Moshiach and in the days of Dovid and Shlomo new converts were not and will not be accepted. The reason for this is that a convert must want to be part of the Jewish nation for spiritual reasons, l'shaim shamayim, and not for ulterior reasons. Therefore when Klal Yisroel is prosperous and strong there is a concern that the convert is converting only to be a part of that success and not to become close to Hashem.
Tosfos explains that this is not a blanket rule. If Bais Din sees that he is serious and wants to convert l'shaim shamayim Bais Din can accept him.
According to this explains Zera Shimshon, Yisro came in order to convert and he had pure intentions. However, he was afraid that Moshe would not accept him since he came only after he heard the miracles that happened to Bnei Yisroel in Mitzrayim, at the Yam Suf and about the falling of the manna. Yisro saw the great benefits of being part of Bnei Yisroel, therefore he was concerned that Moshe would not even want to come greet him. Yisro said that even if Moshe doubts his sincerity, Moshe should still come to greet them because of Tziporah, who had converted at the time when Bnei Yisroel still suffered under the hand of the Mitzriyim and therefore she surely had pure intentions.
The reason Yisro was afraid that Moshe would not come even to greet Tziporah, was that according to one opinion in the Michilta, Moshe actually had divorced Tziporah when he was in Mitzrayim. Yisro therefore told Moshe that he should still come to greet them because of his two children.
Zera Shimshon gives a fascinating explanation based on the writings of the Arizal.
- Rashi in Chumash (Braishis 4/1) quotes the Medrash (Braishis Rabbah 22,2-3) that in the beginning of mankind, Chava gave birth to three girls in addition to her two sons Kayin and Hevvel. One was a twin of Kayin and two were triplets with Hevvel
- It is written in the Medrash that there was an argument between Kayin and Hevel whom had the right to marry the extra girl. Kayin claimed that he had the right to marry her because he was the first born and the first born gets double the inheritance. Hevvel counter argued that since she was born with him, he has the right to marry her. This argument was so heated that Kayin ended up killing Hevvel!
- It is written in the writing of the Arizal that Moshe was the gilgul of Hevvel, Yisro was the gilgul of Kayin and Tziporah was the gilgul of the second girl born with Hevvel about whom Kayin and Hevvel argued. Yisro wanted Moshe to marry in order to return to Hevel (was was now Moshe) to return to Hevvel (who was now Moshe) his triplet (who was now Tziporah) who Kayin married after he killed Hevvel.
- After Kayin killed Hevvel, Hashem exiled him and from Rashi it seems the reason for this was because Hashem judged him as if he killed by shogaig (accident).
- It is written in Mesechta Makkos that a person who killed by shogaig (by accident) and takes refuge in an Eir Miklat cannot return to his previous honor that he had before he went into exile.
- Regarding a person who was exiled to an Eir Miklat, the Rambam writes; although the killer has gained atonement, he should never return to a position of authority that he previously held. Instead, he should be diminished in stature for his entire life, because of this great calamity he caused.
Zera Shimshon infers from the last phrase, "because of this great calamity he caused" that not only one that kills someone cannot to return to "his position of authority" but even one that only caused someone else to be killed.
According to all the above sources Zera Shimshon explains that Yisro was concerned that Moshe would not honor him and come to greet him because he, who was Kayin in a previous gilgul, killed Hevvel and could not be honored. Yisro therefore told Moshe to greet them because of Tziporah.
However, there was also a concern that Tziporah, who was the gilgul of the second triplet of Hevvel, should not be honored because it was because of her that the whole argument that led to the killing started and it seems from the Rambam that even one that only caused a killing cannot return to their previous honor.
Therefore, Yisro said to Moshe; even though Moshe might not come to greet both himself and Tziporah, Moshe should still come because of the children!
