John Gill

Only take heed to thyself,.... To walk according to this law, and not swerve from it: and keep thy soul diligently; from the transgressions and breaches of it: lest thou forget the things which thine eyes have seen; either the statutes and judgments set before them, and the circumstances of the delivery of them; or the punishment inflicted on the breakers of them; or the favours bestowed on those that observed them: and lest they depart from thy heart all the days of thy life; out of thy mind and memory, and have no place in thy affections, through a neglect and disuse of them: but teach them thy sons, and thy sons' sons; their children and grandchildren, that they may be trained up in them in their youth, and so not depart from them when grown up, and in years; see Deu 6:7.