Rashi on Numbers 27:20/רש"י על במדבר כ״ז:כ׳

1ונתתה 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).

2מהודך 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).

3למען ישמעו כל עדת ישראל THAT ALL THE CONGREGATION OF THE CHILDREN OF ISRAEL SHOULD BE OBEDIENT TO HIM — that they should comport themselves towards him with respect and reverence, in the same way as they comport themselves towards you (cf. Yalkut Shimoni on Torah 776).