We find regarding Moshe Rabbeinu that he established the observance of Shabbos for the Israelites while they were still in Egypt. As it is stated in the Midrash (Shemot Rabbah Parsha 1, Siman 28): "And he saw their burdens (Shemot 2:11), he saw that they had no rest. He went and said to Pharaoh, 'One who has a servant, if he does not rest one day a week, he will die. And these are your servants, if you do not allow them one day a week, they will die.' Pharaoh said to him, 'Go and do for them as you have said.' Moshe went and established for them the day of Shabbos to rest." And later, Pharaoh revoked his permission, as stated in the Midrash (ibid. Parsha 5, Siman 18): "Let the work be heavier upon the men (Shemot 5:9), which teaches that they had scrolls with which they would delight from Shabbos to Shabbos, saying that the Holy One, blessed be He, would redeem them, because they rested on Shabbos. Pharaoh said to them, 'Let the work be heavier upon the men and let them labor in it, and let them not regard words of falsehood,' so that they would not delight and rest on Shabbos."

From this we learn that the redemption from Egypt and the future redemption are dependent on faith and Shabbos, and this matter requires explanation.