Deuteronomy 6:7

And thou shalt unfold them to thy children, and meditate upon them when thou art sitting in your houses, at the time when you are occupied in secret chambers, or in journeying by the way; at evening when you lie down, and at morn when you arise.

repeat them over from “a sharp arrow” [Proverbs 25: 18] — and it is well known that an arrow becomes sharp only after continuous, repeated sharpening. From this we see that the essence of Man is the service of God ; and that one serves God by recognizing His works. The Exegetes, upon whom we all rely, have transmitted to us the prescribed times for the reading of the Shma ‘:

when you sit (this adverbial phrase modifies speak of them)

when you lie down to sleep (for no commandments apply to someone who is actually sleeping). Thus we see that speak of them includes both speech and thought.

AND THOU SHALT TEACH THEM DILIGENTLY UNTO THY CHILDREN etc. These clarified commandments have also been alluded to previously, for, since He enjoined in certain commandments, It shall be a perpetual statute throughout your generations;. It is a sign between Me and the children of Israel forever; This is My covenant, which ye shall keep, between Me and you and thy seed after thee — we are thus [obviously] commanded [to see to it] that our children know the commandments, and how shall they know [the precepts] unless we teach them. Similarly, the commandment And thou shalt bind them for a sign upon thy hand, and they shall be for frontlets between thine eyes has already been stated and here he [further] explained and thou shalt bind them meaning that they be placed [upon the arm and head and secured tightly] through tying. It also alludes to the knot [in the strap] of the phylacteries that, according to the tradition received by our Rabbis, is a law declared to Moses on Sinai. He added here the commandment of the Mezuzah — And thou shalt write them upon the door-posts of thy house, and upon thy gates — which is not mentioned there. Perhaps this, too, is [merely] explained [here rather than being an entirely new commandment] since it has been suggested in the commandment, and it be a memorial between thine eyes, that the law of the Eternal may be in thy mouth. is fastened to the upper third of the right-hand door-post, approximately at eye-level, it thus serves as a memorial of the law of G-d, for two portions of the Torah are written on its scroll of parchment. The meaning of the expression and upon thy gates is “and upon the door-posts of the rest of your gates,” such as the gates of cities and countries, similar to within any of ‘thy gates’ [which means “any of ‘your cities’ “].

V'SHINANTAM. An expression of sharpening -- to explain them well, as in (Ps. 64:4), "They sharpened their tongues like swords."

Teach them through repetition and through sharp, intellectual evidence.

And you are to discuss them. For through this you will constantly remember them.

ושננתם, you shall tell them at length.