Deuteronomy 4:9 Only take heed to thyself, and keep thy soul diligently, lest thou forget the things which thine eyes have seen, and lest they depart from thy heart all the days of thy life: ...
Verse 23 is similar which says, Take heed unto yourselves, lest ye forget the covenant of the Lord your God, which He made with you, ...
The phrase "take heed" is used in both passages. It means to be diligent, be watchful, pay close attention to, or take careful notice of. The phrase, keep thy soul diligently, emphasizes that the thing you are to heed affects your soul - your spiritual being. The warning to take heed and be diligent is telling us that something harmful or damaging can happen to us. Just like being on Candid Camera - it happens when you least expect it. There are times in the lives of every one of us when we become smug. We become content with our accomplishments, our morality, etc. We become complacent and self-satisfied. We become lax. It is times like these when we are most likely to err. It is times like these when God's Word warns us to be diligent and take heed.
Israel was warned to take heed, in this particular passage, lest thou forget the things they had seen with there eyes. Lest thou forget the mighty hand of God as He interceded on your behalf - as He protected Israel and led them from Egyptian bondage into the Promised Land. Can you imagine observing God's power as He parted the Red Sea saving Israel and destroying their enemies? How could anyone forget a great incident like that? How could anyone forget the blessings and rewards they received from of God?
On the other hand, how could anyone forget the punishments meted out by God for their disobedience? The Israelites were reminded of God's wrath because of Baal-Peor. (Verse 3). The first few verses of Numbers, chapter 25, describe this incident; how some of the people of Israel, through their association with the Moabites, began to worship their gods and joined themselves to the pagan idol, Baal-Peor. The wrath of God was kindled against them, and He instructed Moses to slay every one that had participated in worshiping the gods of Moab. At Moses commandment, God's punishment was carried out and 24,000 Israelites were slain. How can anyone forget an incident like that? How can anyone forget how severe God's punishments are for those that disobey His commandments?
I'm sure that both of these incidents had an immediate, positive affect on the Israelites that observed them. Just reading about them today should have the same affect on us. However, the passage of time, evidently, takes away some of the lasting affect learned fromincidents such as this. Therefore, we are warned to take heed and be diligent, because it can happen to each one of us. Mankind is capable of forgetting about both the blessings and the punishments that come from God.
The Psalmist (Psalm 78) advises parents to teach their children about both the wonderful and terrible works of God.Asverse 7 states, That they might set their hope in God, and not forget the works of God, but keep His commandments. Availing ourselves to His teachings and the scheduled studying of God's word will help us remember our God and Creator. Teaching and studying that is reinforced with thoughtful and meaningful prayer will help keep us from forgetting God and the eternal salvation promised though obedience to His will.
James 1:22-24 tells us that we should not only hear the word of God, but we are also to do His will. If we are hearers only, we are compared to the person that sees and recognizes their image in the mirror, but after turning away for a while, forgets what they look like. By doing God's will, we will avoid becoming a forgetful hearer.
Take heed - be diligent. Study God's word throughout your lifetime. Do the good works that God wants you to do. Always be a good neighbor to everyone you meet. Continue to do good, charitable works throughout your lifetime. Why is this necessary to take heed? The answer is, Lest thou forget!