שמות ב,יז : וּלְכֹהֵן מִדְיָן שֶבַע בָּנוֹת
The Baal HaTurim notes that the word לכהן appears two other times in Tanach in regard to the Levite that served as a priest for Micah’s idol. This alludes to the saying of Chaza”l that Yisro served as a priest to false deities.
When Moshe married his daughter, he forced Moshe to swear to him that the first son born would also be a priest for false deities. Moshe’s intention was that he knew he would ultimately inspire his father-in-law to change for the good. Yisro was influenced and converted and did not hold Moshe accountable for his oath. Nevertheless, Moshe was punished for making this oath, and his grandson did become a priest to false deities.
Thus, in the verse (Shoftim 18,30) שֶה הוּא וּבָנָיו הָיוּ כֹהֲנִים לְשֵבֶט הַדָנִי עַד־יוֹם נַ גְלוֹת הָאָרֶץ:, there is a tradition to suspend the letter נ of מנשה a bit higher than the other letters of that name. Chaza”l explain that Gershon was the son of Moshe making Yehonason his grandson. Nevertheless, they added the letter נ to Moshe’s name to hang the degradation of idolatry with the degraded one (Manasheh a later King of Yehudah that established idolatry throughout the land).
Chaza”l were protecting Moshe’s honor by not explicitly mentioning his name, similarly to the leaving out of Yaacov in the gemology of Korach.
