Ramban on Vaeira 6:9

English: BUT THEY HEARKENED NOT UNTO MOSES FOR IMPATIENCE OF SPIRIT, AND FOR CRUEL BONDAGE. It was not because they did not believe in Hashem and in His prophet [that they hearkened not]. Rather, they paid no attention to his words because of impatience of spirit, as a person whose soul is grieved on account of his misery and who does not want to live another moment in his suffering even though he knows that he will be relieved later. The “impatience of spirit” was their fear that Pharaoh would put them to death, as their officers said to Moshe, 47 Above, 5:21. and the “cruel bondage” was the pressure, for the taskmasters pressed upon them and hurried them [in their daily task], 48 Ibid. , Verse 13. which gave them no chance to hear anything and consider it.