John Calvin Commentary Genesis 41:14

"Then Pharaoh sent and called Joseph, and they brought him hastily out of the dungeon: and he shaved himself, and changed his raiment, and came in unto Pharaoh." — Genesis 41:14 (ASV)

Then Pharaoh sent and called Joseph. We see in the person of a proud king, as in a mirror, what necessity can accomplish. Those whose circumstances are happy and prosperous will scarcely condescend to hear those whom they esteem true prophets, still less will they listen to strangers. Therefore, it was necessary that Pharaoh's obstinacy should first be subdued, so that he might send for Joseph and accept him as his master and instructor.

The same kind of preparation is also necessary even for the elect, because they never become teachable until the pride of the flesh is brought low. Whenever, therefore, we are cast into severe troubles, which keep us in perplexity and anxiety, let us understand that God, in this way, is accomplishing His purpose of making us obedient to Himself.

When Moses relates that Joseph, before he came into the king's presence, changed his garments, we may from this conjecture that his clothing was poor. To the same point, what is added concerning his “shaving himself,” should, in my opinion, be referred: for since Egypt was a nation of effeminate delicacy, it is probable that they, being attentive to neatness and elegance, preferred to grow their hair rather than cut it. But as Joseph took off his squalid clothing, thus, that he might have no remaining cause of shame, he is shaved. Let us understand, then, that the servant of God lay in filth until the very day of his deliverance.