The first of five couplets in Proverbs 3 is verses 1 & 2. Both verses describe a blessing from God: if you will keep his commandments, you will have long days and peace.
Let’s look at them in detail. Verse 1: Not to forget is to remember, and “remember” in the Old Testament means more than mere cognitive retention. Just like “know” and “fear”, “remember” has a relational and behavioral aspect, and includes obedience. So by saying “remember what I’ve taught you” is another way of saying, “Keep it in your mind and DO it.” By “teaching” he is not specifically referring to the Law in the first 5 books of the Bible, though it includes those. He means any teaching that is of the Law, from the Law, and is an outgrowth of the Law.
You keep it in your heart, consistent with Deut. 6, meaning it is part of your core being. Someone said, “People will be more impressed by the depth of your conviction than the height of your logic.” How true.
If you do this, verse 2 says, you will live long and prosper. Now remember, this is a PROVERB, not a guarantee. Just as we say, “Fools rush in,” it doesn’t mean that every time you make a quick decision you’re an idiot. It’s a proverb, that can be generally true in those situations. It’s a good thing to remember that sometime hasty and rash decisions can come back at you. But we know that’s not always the case, because we also have a proverb that says, “He who hesitates is lost.” So also here. The commands of the Lord are in part at least guidelines for healthy living. All things being equal, those who follow God’s way of living as taught in his Word will live longer than those who flaunt the same commands.
But see, I would have expected him to say that those who keep God’s commands would “find God” or enjoy the benefits of a healthy spiritual life, or something like that. We need to remember that in Solomon’s day, these things (long life and find God) were synonymous. Long life was believed to be the result of knowing God and following his ways, and being righteous. Prosperity was believed to be a clear sign of God’s blessing. So anything that prolonged life and brought prosperity, in their minds, was easily a sign of God’s blessing for a life well-lived. But long life and prosperity are not automatically a sign of God’s blessing, though one hopes that as you live God’s way the result will be long life and prosperity.
Add to that, more than simple longevity is envisioned here. A long life of suffering or strife is not something to be prized, so the writer adds that the life will be characterized by prosperity: a rich and meaningful existence. We all want a life like that. The proverb teaches that our best chance of getting it is living God’s way.