Tafsiran Bilangan 27:20: Rashi, Sforno, Rabbeinu Bahya & Siftei Chakhamim

ונתתה מהודך עליו AND THOU SHALT PUT SOME OF THY GLORY UPON HIM — This refers to the shining of the skin of his countenance (see Exodus 34:29—30).

ונתתה מהודך עליו, you are to confer upon him some of the aura of your regal authority while you are still alive, so that the people will get into the habit of treating him with respect.

ונתת מהודך עליו, “and you will impart some of your stature to him.” This means that Moses was to display some deference to Joshua. According to Baba Batra 75 the important letter in this verse is the letter מ in front of the word הודך, i.e. that Moses was to impart only part of his majesty to Joshua, not all of it. This also reflects the statement by our sages that Joshua compared to Moses much like the moon compares to the sun. Whereas the latter only reflects light received from an outside source the sun generates light. Nonetheless, we must not forget that the sun too received its original input from G’d as we know from Genesis 1,14 where both the sun and the moon are described as מאורות, “luminaries,” as opposed to אורים, “sources of original light.” Moses too had received his initial spiritual input from Hashem.

מהודך SOME OF THY GLORY, and not all thy glory; consequently we learn from this: Moses’ face beamed like the sun, Joshua's face only like the moon (Sifrei Bamidbar 140:2; Bava Batra 75a).