The parsha ends with Yosef Hatzadik asking the sar hamashkim to repay the kindness he showed him by remembering to try to get him out of prison. The sar hamashkim forgets all about Yosef for two years. According to the medrash, this forgetting was not a mere coincidence, rather Yosef was punished with remaining in prison an additional two years for lacking proper bitachon. Yosef should not have requested anything of the sar hamashkim.
The commentaries find this medrash very hard to understand - isn't it always expected of us to do our hishtadlus and act as if there were no hashgacha pratis? At the beginning of parshas Vayishlach we read that Yaakov Avinu prepared himself for his meeting with Esav not only with tefillah, but also with doron and milchama. What was wrong with Yosef asking the sar hamashkim to try to get him released from prison?
To understand this medrash we must understand what exactly does bitachon really mean. The Chazon Ish points out that while many think that bitachon means that one in a dangerous predicament should always have the attitude that everything will work out well in the end, this understanding can not be correct. Why should one assume that the danger will pass without affecting him - was he notified of this by a navi?
Included in emunah is belief in hashgacha pratis. Chazal (Chullin 7b) tell us that "No one hurts his finger in this world if such was not ordained from above" and "No one can touch anything that was intended for someone else" (Yoma 38b.) Records are kept in heaven on all people, and everyone will get what he deserves. We have emunah (we believe) that whatever will happen to me is the will of Hashem. Whether I survive or not is up to Hakadosh Baruch Hu, and I can not possibly suffer if this is not the wish of Hashem.
Bitachon requires that we act in accordance with our emunah, i.e. in accordance with this principle of faith that there is hasgacha pratis. While one must engage in hishtadlus, he should not fall to pieces considering the possibility that he may accidentally (i.e. not in accordance with the divine will) die, etc. The outcome of all situations is dictated by the will of Hashem, and everything Hashem does is ultimately l'tov.
The Egyptians of old were known as an ungrateful bunch. As such, for Yosef to ask the sar hamashkim to remember him was grasping at straws; it was a totally ineffective act which would only be engaged in out of desperation. One who has emunah in hashgacha pratis would always maintain his calm and never fall to pieces. Bitachon means that one acts in accordance with his emunah in hashgacha pratis. Losing one's calm and falling into a state of desperation indicates that one's belief in hasgacha pratis is not really that strong.
Baruch merachim al ha'aretz - we believe not only in hasgacha klalis, that Hashem looks after the entire world with an overall perspective, but also in barcuh meracheim al habriyos, that He looks after each person individually, i.e. with hashgacha pratis.