Deuteronomy 32:46
And he said unto them, Set your hearts unto all the words which I testify among you this day, which ye shall command your children to observe to do, all the words of this law. And he said unto them, Set your hearts unto all the words which I testify among you this day, which ye shall command your children to observe to do, all the words of this law.
Moses spoke this charge after reciting his song to the people. It calls for setting the heart on all the words God testifies, taking them to heart and obeying the whole law, and commanding children to observe and do every part of it. Those words include definite instruction given to Israel about habits of life covering both physical and spiritual well-being.
The way of God's commandments is the way of life: obedience is not empty or useless but is the people's life, giving life and health to the flesh. God gave His commandments to prolong life, promising health and prosperity and prolonging days in the land across the Jordan they were going to possess, and preserving Israel from the evil practices of nations that did not know the true God. God's laws are not arbitrary exactions, and every Thou shalt not in physical or moral law implies a promise that blessing will attend obedience, including the assurance of taking away sickness on condition of obedience.
God never forces obedience but seeks to save from evil and lead to good. The call is to choose the right side, connect with heavenly agencies, and adopt the principles of life revealed in the written Word and in nature that restore the divine image; it is man's work to learn these principles and by obedience cooperate with God in restoring health to body and soul, reaching the standard of perfection made possible by the gift of Christ, since the full blessings of obedience come only by receiving the grace of Christ which gives power to obey. The instruction applies across generations to parents: when parents fail to teach and obey God's commandments, disregard for God and His Sabbath spreads and rebellion follows, while diligent teaching and obedience would avert that outcome. Keeping God's commandments, including observing the true Sabbath, marks those who serve Him, keeps His people in covenant with Him, and prepares them to receive His blessings through severe trials.