The strength that would be harsh or brutal is eliminated by the charge given in this verse. Yet, David’s charge to Solomon points higher than himself to the charge of the Lord your God.
David told Solomon to keep this charge. Using a verb that he would return to again, David charged Solomon to keep
that charge that God had given his people. The word has the sense of the fulfillment of an obligation.
The parallel expression that David used was to exhort Solomon to walk in God’s ways. David used the term walk
to indicate the manner in which Solomon would conduct himself. This would determine what path (or way) he would follow.
David did not exhort his son to a mere outward obedience but a heartfelt keeping of the Lord’s charge reflected by the outward life. So-called obedience that is just for show is not obedience in any true sense, but obedience that starts in the inner person will demonstrate itself in outward behaviour.
David continued in his exhortation as he describes how keeping Yahweh’s charge would play out in Solomon’s life. He is to keep a number of specific things that are all contained in the law of Moses—statutes, commandments, rules, and testimonies. David did not expect Solomon to exegete each specific term. The Lord’s guide to Solomon was found in the whole of the law of Moses. If Solomon kept the law in its entirety, he would have kept all these individual ways of describing the multi-faceted character of the law.
David told his son what the result of such obedience would be. He would prosper in everything. This prosperity would discover itself in Solomon’s actions and the choices he would make for future actions.
Many commentators see a reflection of the message of Deuteronomy in David’s words at this point, and I believe rightly so. They find the source of David’s words particularly the blessings that Moses promised Israel on the plains of Moab before his death and their entrance into the land of promise (Deuteronomy 31:1–34:12).
Nevertheless, we should not follow those who use the similarity as evidence that there is a literary connection between the writer of 1 and 2 Kings and the writer of Deuteronomy. There is no reason to believe that we should attribute these words to the writer rather than to David. All commentators seem to accept that David’s practical political advice that follows begins in 1 Kings 2:5. Why separate the exhortation as coming from two different sources?
3 and keep the charge of the LORD your God, walking in his ways and keeping his statutes, his commandments, his rules, and his testimonies, as it is written in the Law of Moses, that you may prosper in all that you do and wherever you turn,