"And he said to Moshe..." (Shemot 18:6)
It is brought in the Midrash Rabbah (Shemot Rabbah 27:2) that HaKadosh Barukh Hu said to Moshe: "I am the one who brought Yitro close and did not distance him. This man who has come to you, came only for the sake of Heaven."
It is necessary to reflect on why HaKadosh Barukh Hu had to tell Moshe that Yitro had come with a purely spiritual intention.
This can be explained in light of what the Gemara teaches (Yevamot 47a): "Converts are not accepted in the days of the Messiah (once the Messiah has already been revealed), for fear that they are converting only due to the greatness and prestige of Israel, and not for sincere reasons. Therefore, they are not accepted." However, the Tosafot clarify that when it is evident that their intention is genuinely for the sake of Heaven, they are indeed accepted.
Thus, since Yitro came to join Israel after the exodus from Egypt, the Giving of the Torah, the war against Amalek, the descent of the Manna, and the Well of Water — a time of great elevation and prestige for Israel — Moshe feared accepting him as a convert. Therefore, HaKadosh Barukh Hu told him explicitly: "This man who has come to you has come for the sake of Heaven, and therefore you must accept him with full confidence."
(Zera Shimshon, Parashat Yitro, Art. 2)
