In the beginning of Parashat Bo, God tells Moshe that He brought the plagues upon Pharaoh and Egypt so that Benei Yisrael will tell of God’s unlimited might to their children: “…and in order that you tell unto your son and grandson of how I made a mockery of Egypt and of My wonders which I performed among them, and you shall know that I am the Lord.”
Rav Yehoshua Rokeach of Belz (the second Belzer Rebbe) found it significant that after God expressed His wish that Benei Yisrael tell their children and grandchildren of His wonders, He then added, “and you shall know that I am the Lord.” God told Moshe that His objective is not only for the people to tell their offspring about these miracles, but also to reinforce their own faith in the Almighty and His control over the world. The simple explanation, seemingly, is that this concluding phrase – “and you shall know that I am the Lord” – describes the end of result of parents teaching their children and grandchildren about the miracles of the Exodus. If every parent assumes this responsibility, then this will result in Benei Yisrael collectively “knowing” about God’s power. God wanted every parent to tell his or her children about the miracles of the Exodus so that Am Yisrael as a whole will live with firm and unwavering faith in the Almighty. (It should be noted that the concluding phrase is written in the plural form – “vi-ydatem” – whereas the verse opens in the singular form – “tesaper…binkha u-ven binkha.” This might imply that, as we explained, the beginning of the verse addresses individual parents, whereas the end of the verse speaks of the nation as a whole.)
The Rebbe of Belz, however, suggested that the phrase “and you shall know that I am the Lord” was added as a precondition to the instruction to “tell unto your son and grandson.” In order for us to inspire the next generation and teach them the principles of faith, we must first strengthen our own knowledge and commitment. Our success in the effort to teach, guide and uplift others requires that we also make an effort to uplift ourselves. Bolstering our own devotion to God is a necessary prerequisite for our desire to bolster that of others by exerting a positive influence and teaching and inspiring the next generation. And thus as God commands us to teach our children about the Exodus, He emphasizes that “you shall know that I am the Lord” – that we must constantly work to raise and uplift ourselves, even as we work to raise and uplift our children and everyone around us.