John Calvin Commentary Genesis 37:9

"And he dreamed yet another dream, and told it to his brethren, and said, Behold, I have dreamed yet a dream: and, behold, the sun and the moon and eleven stars made obeisance to me." — Genesis 37:9 (ASV)

And he dreamed yet another dream. The scope of this dream is the same. The only difference is that God, to inspire greater confidence in the oracle, presents him with a figure from heaven. Joseph's brothers had despised what was said concerning the sheaves; the Lord now calls upon them to look towards heaven, where his august Majesty shines forth.

However, it may be asked how it can be reconciled with the fact that his mother, who was now dead, could come and bow down to him. The interpretation of certain Hebrews, who refer it to Bilhah, is unconvincing, and the meaning appears plain without such contrivances: for the sun and moon designate the head of the family on each side. Thus, in this figure, Joseph sees himself reverenced by the whole house of his father.