Based on the writings of Rav Chaim Cohen, the Chalban, Tallelei Chaim, Sefer Shmos, p. 519. Bitachon (trust) vs. hishtadlus (effort) is one of the most misunderstood concepts in all of Torah. The main source of resolving the issue of trust versus effort is found in parshas Vayishlach where Yaakov prepares to meet Esav. Why was Yaakov afraid of Esav, and what is the difference between Yaakov Avinu, who was praised, on the one hand, and Avraham Avinu and Yosef HaTzadik who were both punished for "apparently" questioning (Avraham) and making an effort (Yosef). The seven submissive bowings of Yaakov before Esav. We have a halachic norm that Hashem never reneges on a positive promise, as opposed to void an evil decree. But in Yaakov's view Hashem could retract if he or his children were unworthy. If Hashem promised Avraham that his children would inherti the land, why did Avraham question Him? Parenthetically, this is the way we test to see if a prophet is a Navi sheker (false prophet). In the time of Haman (Purim), the Jewish people were not worthy, learned from Yaakov Avinu, and were worried that they would be wiped out; thus, why should they have bitachon.