פירוש על דברים 32:44

הוא והושע בן נון HE AND HOSHEA THE SON OF NUN — It was the Sabbath of transmission of office (lit., “of two pairs” of judges): authority was taken from one and given to the other (Sotah 13b). Moses appointed a Meturgeman for Joshua that he (Joshua) should hold in public an Halachic discourse during his (Moses') lifetime in order that the Israelites should not say to him, “During your teacher’s lifetime you did not dare to raise your head!” — And why does it (Scripture) here call him Hosea (since his name had long since been changed to that of Joshua — cf. Numbers 13:16)? In order to indicate that he did not become haughty, for although this dignity had been conferred upon him, he assumed a humble bearing as at the commencement of his career (cf. Sifrei Devarim 334:3).

And Hoshe’a. He was only named Yehoshua due to Moshe’s prayer that Hashem should save him from the plot of the spies. As long as there were people from that generation alive, he was called by the name Yehoshua. However, once all of that generation had died out, there was no longer a need to call him by that name, and Moshe returned to calling him Hoshe’a.

הוא והושע בן נון, "he and Joshua son of Nun." Although Joshua stood beside Moses, G'd's word came only to Moses, as is plain from the words וידבר ה׳ אל משה in verse 48. Although Moses had added the letter י to Joshua's name in Numbers 13,16, this was in order to lend him prestige vis-a-vis Israel. When G'd mentions Joshua's name, it remained unchanged as it was not appropriate to make him look prestigious vis-a-vis his teacher (Compare Isaiah 10, 15: "Is the axe going to boast in the presence of the wood cutter?").