וַיֵּצֵא מֹשֶׁה לִקְרַאת חֹתְנוֹ, וַיִּשְׁתַּחוּ וַיִּשַּׁק-לוֹ, וַיִּשְׁאֲלוּ אִישׁ-לְרֵעֵהוּ, לְשָׁלוֹם; וַיָּבֹאוּ, הָאֹהֱלָה- And Moshe went out to meet his father-in-law, and they bowed down and kissed him; and they asked each other of their welfare; and they came into the tent. (Exodus 18:7)
In response to the question of who is the ‘they’ who bowed down to Yitro along with Moshe, Rashi says ‘a great honor was bestowed on Yitro that at the same moment that Moshe went out to greet him, so did Aaron.’ The Torah says explicitly that Moshe went out to meet his father-in-law, but from where does Rashi have proof that Aaron did, too? Elsewhere we learn that the use of the root י.צ.א (go out) is used instead of the word ה.ל.כ (go) to express that the Shechinah (Gd’s presence) leaves a place with the tzadik to whom the word refers. Accordingly, the words וַיֵּצֵא מֹשֶׁה (And Moshe went out) tells us that the Shechinah also went out of the Israelite camp. However, was a prophet as great as Aaron in the Israelite camp then the Shechinah would not have left the camp with Moshe. Since we know that Gd’s presence did leave the camp, we know that Aaron must not have been in the camp. Thus, Rashi teaches that the person accompanying Moshe in bowing down to Yitro had to be Aaron.
