What is the meaning of "va'Yakam Edus b'Yakov"?
Radak: Just like one must mention the wonders and inform the children, so one must inform them of the Torah and testimonies that Hashem put in Yisrael that he took them out of Egypt.
Malbim: The stories of the Torah are called Edus. They testify to true matters, e.g. the creation, the flood, the punishment of Sedom and [Dor] ha'Flagah, stories of the Avos and redemption from Egypt. What we learn from them is called Torah. Under these stories are hidden exalted matters from secrets of the creation and Elokus, from Ma'ase Bereishis and Merkavah and matters like them. This testimony was established in Yakov, the commoners.
Why does it say "v'Sorah Sam b'Yisrael"?
Radak: Yisrael are the Gedolim. Our fathers are commanded to tell both of these (Edus and Torah) to their children.
Where did Hashem command to tell children?
Radak: "V'Hodatam l'Vanecha" (Devarim 4:9).
