And thou shalt teach them diligently unto thy children, and shalt talk of them when thou sittest in thine house, and when thou walkest by the way, and when thou liest down, and when thou risest up. Thou shalt teach them diligently - שננתם shinnantam, from שנן shanan, to repeat, iterate, or do a thing again and again; hence to whet or sharpen any instrument, which is done by reiterated friction or grinding. We see here the spirit of this Divine injunction. God's testimonies must be taught to our children, and the utmost diligence must be used to make them understand them. This is a most difficult task; and it requires much patience, much prudence, much judgment, and much piety in the parents, to enable them to do this good, this most important work, in the best and most effectual manner. See at the end of this chapter, Deuteronomy 6:25 (note).
And shalt talk of them when thou sittest in thine house - Thou shalt have religion at home, as well as in the temple and tabernacle.
And when thou walkest by the way - Thou shalt be religious abroad as well as at home, and not be ashamed to own God wheresoever thou art.
When thou liest down, and when thou risest up - Thou shalt begin and end the day with God, and thus religion will be the great business of thy life. O how good are these sayings, but how little regarded!