The Posuk says:
וּלְמַעַן תְּסַפֵּר בְּאָזְנֵי בִנְךָ וּבֶן בִּנְךָ אֵת אֲשֶׁר הִתְעַלַּלְתִּי בְּמִצְרַיִם וְאֶת אֹתֹתַי אֲשֶׁר שַׂמְתִּי בָם וִידַעְתֶּם כִּי אֲנִי ה
If your are telling your children, why does the pasuk say "you will know"?
At first glance, it should say "and your children will know"?
The CHIDA answers based on a gemara in Baba Metziah that if a person his son and his grandson are all Torah Scholars the torah will not leave from his generations, Tosfos adds this is when the grandfather sees the next generations and this is what our posuk is telling us When you tell it to your son and your grandson then Like the gemara guarantees YOU will know you have Talmidie Chachamim as Hashem will be in their Consciousness
Reb Sholom of Belz asks the question also, but has a different approach.Much like a Rebbi when he relates Hashems wonders strengthens himself in emunah(yahu i Imagine you can Vouch for that) so to when a father tells of Hashems greatness he by proxy will gain strengthen in his Emunah
