vayeishev

after yosef interprets the dream for the butler he says to him: " please do me a favor and mention me to Pharaoh and get me out of this prison - but the butler did not remember yosef. and he forgot him". rashi comments that yosef was punishment for relying on a human being by remaining in prison another two years.

one might ask a simple question; why was yosef punished? obviously the butler and the baker had their dreams in order for yosef to explain it. later when Pharaoh will have his dream yosef will come to the attention of the king as a dream interpreter and will be brought out of prison.

chassidus explains that yosef was on a very high level and was not allowed to do what the average person may and must do; work through nature. yosef was above nature and needed only to rely on hashem!

 or another way to look at this was the fact that he asked for the help! yosef understood that hashem made the butler and baker  have dreams and allowed him to understand their meaning was meant to assist him in leaving the prison. his sin was not in seeing that they would be the vehicle through which he would be helped but in asking them to help him. he should have just explained the dream to them  and relied on g-d alone to unfold the events as He saw them fit to develop.