Vaera: why didn't the Jews listen to Moshe?
The Torah's (Vaera 6:9) answer to the title question is: velo shamu el Moshe mikotzer ruach umeavoda kasha [they didn't listen to Moshe because of shortness of breath and hard work]"
The Rashmbam explains the stress is on now. Even though they believed at first when they thought that they were facing a reprieve from the hard work, now that it got even harder, they lost faith.
The Ramban's interpretation is that it doesn't mean that they didn't believe in Hashem and in his prophets, only that they didn't pay attention to His words because of their shortness of breath like a man whose who is so sick of suffering from his toil that he wouldn't want to live another minute in it for the sake of something better afterwards.
My grandfather's take is that this is the view of Rashi who in his pure language explains that velo shamu el Moshe means that they didn't accept any tanchumin [comfort].
The Midrash Rabbah explain that they didn't listen to Moshe because it was diffidult in their eyes to remove themselves from the practice of idolatry.
Taking all these together, my grandfather insists that there is no real contradiction among the interepretations of the Midrash, Rashi, and Ramban, for, certainly, ayn mikrah yotzeh miyedey pshuto [a text is never divorced from its plain meaning]. Accordingly, the plain meaning of the text velo shamu el Moshe mikotzer ruach umeavoda kasha [they didn't listen to Moshe because of shortness of breath and hard work] stands.
However, applying the Midrash clarifies that were it not for the hard work, they would have found it feasible to remove themselves from idolatry. They did have faith in Hashem and His prophets. What the Midrash comes to teach us is what was the inner cause, the primary source of their refusal to listen. The same kind of revelation comes across with respect to the text's report on Yitzchak's love for Esav (see http://kallahmagazine.blogspot.com/2015/11/toldos-torah-reveals-motivations.html)
The footnote here refers to the Mechilta on Parshas Bo It starts with the question: How could the Israelites not pay attention? Wouldn't anyone told good news about his future be happy to hear it? Here they were told that they would be going free, so how could they not rejoice? The answer is that it was difficult in their eyes to leave idolatry. The lack of happiness and attentiveness here was not due to a lack of faith but in a reluctance to leave idolatry.
As for the Rashbam? My grandfather takes it as pointing to different levels of faith. They had a higher level at the point when it say, vayamen ha'am [the nation believed] that they fell from at this poitn.
Related post: http://kallahmagazine.blogspot.com/2016/01/what-do-you-know.html