Deuteronomy 6:17

Ye shall diligently keep the commandments of the LORD your God, and his testimonies, and his statutes, which he hath commanded thee.

Diligent keeping means carefully keeping all that God has commanded under commandments, testimonies and statutes, from the greatest to what may seem least, with none of His Word neglected.
It was spoken by Christ Himself to Moses for Israel brought into a land of abundance with cities, houses, wells and vineyards, where they must not forget the Lord who brought them from Egypt, but fear and serve Him alone and not test Him.
What God required of His ancient people that they might be holy is required now, and fully kept as commanded it becomes righteousness and is the decided condition of salvation and eternal life by keeping the ten precepts of supreme love to God and unselfish love to neighbor.
Obedience brings the richest blessing, prosperity, good and protection, and studying this requirement in Deuteronomy 4-8 is profitable now because the day of God's final review is near when every character will be investigated and every case decided for eternity.
Keeping now means parents first keeping themselves and then teaching children diligently at all times, honoring the seventh-day Sabbath and God's laws of health, and coming into unity by subduing self, while neglect of this teaching lets the false claim that the law is abolished pass from generation to generation.

Words and Setting

The verse commands diligent, careful keeping of all that the Lord has commanded under three terms — commandments, testimonies, and statutes — with all His directions to be carefully observed from the greatest to what may seem least. None of the important things in His Word are to be neglected, and the charge is given in positive words full of assurance. The command was spoken by Christ Himself to Moses from the pillar of cloud.

Its setting is Israel brought into a land of abundance with cities, houses, wells, vineyards and fullness. There in fullness they must not forget the Lord who brought them out of Egypt from the house of bondage, but fear Him and serve Him alone, reject other gods, and not test Him as at Massah.

In its immediate context the keeping is tied to doing what is right and good in God's sight, receiving good and well-being, and going in to possess the land promised to the fathers. Fully kept before the Lord as commanded, this keeping is counted as righteousness, and the commands are to be kept for the people's good and preservation. Parents are directed to explain the commands to their children by recalling the deliverance from Egypt and God's care, teaching them diligently from earliest years alongside the fear of the Lord, and this includes honoring the Sabbath and doing what is right and good before God with His protection.

Requirement and Blessing

What was required of ancient Israel in order to be a holy people to God was diligent keeping of His commandments and His testimonies and His statutes, and that same requirement rests upon His people now. Fully kept before the Lord as commanded, such keeping becomes righteousness. Love of self must give way to full obedience, and where self-love remains supreme deficiency in fulfilling the law of God is exposed.

This keeping states a decided condition of salvation and eternal life by keeping the ten holy precepts. Those precepts are summed as loving God supremely and neighbor as self, in unselfish duty to God and fellow men instead of idolizing possessions. It is the same condition given to the lawyer who asked what to do to inherit eternal life and to the young ruler who asked what to do to enter into life. It puts everyone to the strenuous task of diligently inquiring and searching God's Word to know and do the prescribed conditions at peril of the soul.

The words commanding this keeping are positive and full of assurance, and obedience to the statutes thus specified brings the richest blessings. That obedience is part of doing what is right and good in God's sight, and it is tied to well-being and good, to going in to possess the promised land, and to receiving God's protection. This includes honoring the Sabbath by keeping the seventh day holy as commanded rather than substituting another day, and children are to be taught the commands and their meaning, including how God delivered Israel from Egypt.

Studying this requirement as set forth in the fourth through the eighth chapters of Deuteronomy is profitable now. The day of God's great final review is near, when the people of this world must stand before the Judge of all the earth to answer for their deeds. The present is the time of investigation, when before that day every character will have been investigated and every case decided for eternity, so these words are to be read as preparation for that judgment.

Present Duty and Application

Diligent keeping begins with parents themselves and then extends to diligent teaching of children from infancy and earliest years at all times. The commandments, testimonies, and statutes are to be kept constantly before the people as frontlets between the eyes and written on houses and gates, to keep them from every false way. That training aims to form characters that meet God's approval, taking every precaution to prevent objectionable traits of character from growing up in them. Such work starts with entire surrender of the soul, with self-control for the Creator and Redeemer, cleansing the soul-temple, trimming the inner lamp, and revealing piety, virtue, and godliness in the home life. The fear of the Lord, which is the beginning of wisdom, belongs to this early instruction, for without a holy root there can be no acceptable fruit and God will not accept service from an unconsecrated offerer, and only those thus prepared for the present and the future life will be admitted into the city of God.

Keeping now includes honoring the Sabbath and doing what is right and good before God, connected with well-being, protection, and possessing what He promised. This means keeping the seventh day holy as God commanded rather than substituting another day, and teaching the Sabbath from Scripture, traced from Creation to the New Earth, on the plain authority of God's Word as the basis for meeting opposition. The same diligence includes respecting God's laws of health, since transgressing those laws brings His displeasure. Walking carefully, denying self, and practicing Christlike virtues belong to faithful obedience and open the way to receive more of the Holy Spirit.

Diligent keeping now means coming into unity with brethren, removing every difference, subduing self, self-esteem and self-confidence, correcting weakness of character, and fitting for service in the Lord's work so the enemy will not be master. All directions are to be carefully observed, from the greatest to those that may seem least, and this applies to those carrying responsibilities in work such as sanitarium work, where humble faithfulness is connected with success. None of the important things specified in God's Word are to be neglected, so people must study Scripture for themselves and diligently inquire to know and do the prescribed conditions, lest they be found in rebellion. That diligent inquiring and searching of God's Word to know and do its conditions is laid as a strenuous task at peril of the soul.

Neglect of the parental duty to teach God's law allows false claims that the law is abolished to pass from generation to generation. That neglect and rejection of God's law is connected with the controversy over the Sabbath.