Albert Barnes Commentary Deuteronomy 11:2

"And know ye this day: for [I speak] not with your children that have not known, and that have not seen the chastisement of Jehovah your God, his greatness, his mighty hand, and his outstretched arm," — Deuteronomy 11:2 (ASV)

And know ... - Understand it this way: And acknowledge this day (for I am not addressing your children who have not known and who have not seen) the chastisement of the Lord, his greatness, and so on.

The “chastisement” consisted in the many mighty acts, both of punishment and mercy, through which God had guided them from Egypt to the borders of the promised land.