And so that you should relate in the ears of your son and your son’s son that I have mocked Egypt’ (10:2)
In this verse, Hashem is telling Moshe the purpose of further plagues against Egypt. Why does the verse include the seemingly superfluous words “relate in the ears of your son. . .” why not simply say “relate to your son”?
The Ohr Hachaim explains that the purpose of the plagues was not to bring revenge upon the Egyptians — which could have been done in any natural way in this world or the next — rather it was solely for our sake. Specifically, to inculcate within the Jewish People throughout the generations that Hashem controls every aspect of nature and that anyone who harms His children will receive a punishment like no other.
With this, we can further understand Rav Yosef Shlomo Kahaneman’s answer to our question regarding the additional words “relate in the ears of your son.” He explained that there are times when we can say something to someone and it will be heard, but if there is a lot of background noise we have to shout, and when the outside noise is still too great, then we have to say it directly into someone’s ears. This is the message that we are being told in this verse. Knowing that Hashem runs every aspect of the world, and that everything is accounted for, and that He loves us even more than a father can possibly love his child is what we need to tell our children, grandchildren — and of course, ourselves. But the outside noise — today’s society which rejects and confuses these points and leaves people without a meaningful connection to Hashem — is causing this message not to be heard. Therefore, it is incumbent upon ourselves, especially as parents, to cut out this background interference and relate this message: Hashem is in charge, He loves us, and nothing that happens — good or bad — escapes His attention. If we can pass on this message, despite the world’s loud noises that attempt to quash it, then we have fulfilled the purpose of the plagues all those years ago.
 See the Ohr HaChaim for an explanation of why both aspects are necessary and how each of the plagues achieved this desired result (Shemos 10:1-2).