And he said unto them
By way of exhortation:
set your hearts to all the words which I testify among you
it was not enough to hear them, but they were to lay them up in their hearts, and retain them in their memories; and not only so, but reflect on them in their minds, and closely apply to the consideration of them, and get the true knowledge and sense of them, and put it in practice:
which ye shall command your children to observe, to do all
the words of
which shows that the exhortation does not respect the song only, but the whole law delivered in this book; which they were not only to attend to themselves, but to transmit to their children, and enjoin them the observance of, that so religion might be perpetuated in their posterity.