The Torah in Parashat Shemot tells the famous story of Moshe’s rescue from Pharaoh’s decree requiring that all newborn Israelite boys be killed. His mother placed him in a basket in the river, where he was eventually found and saved by Pharaoh’s daughter. The Torah relates that when the princess opened the basket, she saw “na’ar bokheh” – a child crying (Shemot 2:6).
The Gemara in Masekhet Sota (12b) cites a debate among the Tanna’im regarding the Torah’s use of the word “na’ar” in this context. This word generally refers to a “lad” – an adolescent – and not an infant, and thus its usage in this verse led Rabbi Yehuda to conclude that Moshe’s voice as an infant resembled that of an adolescent. Pharaoh’s daughter is described as having discovered a “na’ar” crying because Moshe’s voice was that of an older boy. Rabbi Nechemya objected to this interpretation, retorting, “If so, then you have turned Moshe into a blemished person!” Unable to accept such a notion, Rabbi Nechemya explained the term “na’ar” to mean that Moshe’s mother made a “chupat na’arim” – something resembling a canopy that is used for a wedding, recognizing that she would likely never see him get married.
Rashi explains Rabbi Nechemya’s argument as claiming that according to Rabbi Yehuda, Moshe had the halakhic status of ba’al mum (blemished person) with respect to the service of the Leviyim in the Beit Ha-mikdash. The Leviyim were assigned the role of singing in the Beit Ha-mikdash, and an unusual voice constituted a “blemish” which disqualified a Levi from serving this role. Rabbi Nechemya could not countenance the possibility that Moshe, the most distinguished member of the tribe of Levi, would have a blemish that would disqualify him for the Leviyim’s role.
A number of writers (including Rav Yitzchak Sorotzkin, in his Gevurat Yitzchak commentary to Masekhet Sota) noted that the point of disagreement between these two Tanna’im may be understood in light of the Rambam’s formulation of the law disqualifying a Levi who cannot sing properly. In Hilkhot Kelei Ha-mikdash (3:8), the Rambam writes that unlike kohanim, who become disqualified for their roles in the Beit Ha-mikdash if they develop a physical defect, Leviyim are not disqualified on account of physical defects. The Rambam writes that a Levi is disqualified only “when his voice is tainted due to old age” (“ke-she’yitkalkeil kolo mei-rov ha-zikna”). The clear implication of the Rambam’s ruling is that a Levi with vocal defects is allowed to sing in the Beit Ha-mikdash, as it is only the effects of old age on a Levi’s voice that disqualify him for this role.
According to the Rambam, then, a young person with an unusual voice is not considered a ba’al mum with respect to the Leviyim’s singing. Possibly, this was the position taken by Rabbi Yehuda, who was not troubled by the prospect of Moshe having a peculiar voice. He felt perfectly at ease interpreting the verse to mean that Moshe as an infant had the voice of a young adult, because an unusual voice does not constitute a “defect” for a Levi unless it is caused by old age. Rabbi Nechemya likely disputed this presumption, and maintained that any unusual voice disqualifies a Levi, and for this reason he rejected the possibility that Moshe had an unusual voice.
Rashi, in his commentary to this verse, cites Rabbi Yehuda’s interpretation, that Moshe’s voice as an infant resembled that of a grown lad. Already the Ramban questions why Rashi disregarded Rabbi Nechemya’s contention. The answer, perhaps, is that Rashi, like Rambam, accepted the view that only a voice tainted by old age disqualifies a Levi from singing, and not another kind of vocal abnormality. Therefore, Moshe was not considered “blemished” as a result of his unusual voice.