What the Holy One, blessed be He, did, in  bringing so many plagues upon them was so that it be recounted to the children, as it says: "That you may tell in the ears of your child". Not that He could not have taken them out at once, Heaven forbid, but so as to display His mighty hand. This is why Moses refused to go, and asked, "Why have You dealt ill with this people?", for he thought that the Holy One, blessed be He, should wait for the time of their redemption, and release them immediately in a single undertaking. God therefore informed him of the time of Redemption - "that you may tell", as explained above…So it is in our day. We have seen His mighty hand and outstretched arm and He will fulfill what it says in Scripture, "I will show him wondrous deeds, as in the days when You sallied forth from the land of Egypt". Amen, may it be Thy will.