Joseph, because he merited to the level of ‘the Righteous-One’,☉Yesod the ‘life-force∞ḥaiy (=18) of the worlds’, through which one is required to worship with all the sephirot – towards the Shekhinah – he merited this dream. It is this that is written: (Gen. 37:9)... and behold, the sun and the moon... etc.
And a prophet who ascends to this level, the sun and moon and stars and constellations, all confer prophecy to his soul, and the spirit of prophecy, to prophesy, from all of them.
And this is the meaning of... bowing down to me. (ibid.) Because from all of them does prophecy descend to him, and from all of them is his soul comprised, and that is the reward of these ‘masters of the stature’.