“These Words Shall Be on Your Heart”: A Call to Careful Devotion

There are two small words we slip into conversation so casually we barely notice how often they appear. When your husband leaves home in especially bad weather, when your teenager heads out late at night, when someone you love is about to step into an uncertain or harmful situation, you say them almost automatically: be careful. 

What you’re saying to your loved one is . . .

I care about you.
I’m concerned about your safety.
I don’t want you to get hurt. 

Moses uses a similar expression more than twenty times in the book of Deuteronomy. In the context of this part of the Old Testament, it’s tempting to read the phrase as little more than a stern legislative warning. But while Deuteronomy is a book of the Law, it’s also Moses’ farewell address to a people he has shepherded for forty years. His caution to “be careful” isn’t a cold command. It is the language of a faithful shepherd—protective, pastoral, and rooted in love—meant to guard Israel’s faith and, through the preserving grace of God’s Word, to guard ours as well.

The Cost of Ignoring the Call to “Be Careful”

We’ve all seen what happens when someone isn’t careful. Sometimes the consequences are small: a bruised ego, a minor repair, or a slightly embarrassing moment. Other times the fallout is heavier, causing irreparable damage, broken trust, or pain that could have been prevented. 

For Israel, the consequences were profound. Moses didn’t live to see whether or not the people heeded his warnings, but the rest of Scripture reveals what unfolded in the generations that followed.

It wasn’t until I studied Deuteronomy more closely that I realized that Israel’s failure to remember and apply the words of this particular book helps explain what happens throughout the rest of the Old Testament. As I was reading through the introduction to Deuteronomy in The Moody Bible Commentary, I was struck by the connections that were made. Here’s what it said:

• “Deuteronomy explains the success of Joshua and the failure of the period of the judges. To have success, Joshua was instructed (Josh. 1:8) to meditate and keep ‘this book of the law’ (i.e., Deuteronomy). Joshua faithfully executed the teaching of this book, even to the point of conducting a covenant renewal ceremony at the end of his life. . . Joshua was successful because he knew and lived Deuteronomy. The complete opposite happened in the period of the judges. It was a chaotic period, full of flawed leaders when ‘everyone did what was right in his own eyes’ (Judg. 21:25). In that time period Israel was not doing what was right according to ‘the book of the law,’ and so it experienced failure.”¹

• “Deuteronomy explains the success and failure of the Israelite kings (Deut. 17:14–20). Each king was to handwrite his own personal copy of the ‘book of the law’ . . . That way he could not feign ignorance of God’s commands. King David most likely followed this injunction (Psalm 1; 19; 119), whereas his son Solomon did not (cf. Deut. 17:16–17 with 1 Kings 10–11). Jeroboam clearly violated the commands of Deuteronomy in 1 Kings 12, and this was later true of other evil kings (1 Kings 15:34; 16:26).”²

• “Deuteronomy explains the existence of many prophets in the eighth to sixth centuries BC. Israel’s spiritual decline caused God in His grace to send prophets, who in essence said: ‘Read and heed Deuteronomy.’ . . . All the prophets, especially Hosea, Jeremiah, and Daniel all beat with the same heartbeat of Deuteronomy.”³

• “Deuteronomy explains the reason for the Babylonian exile (Deut. 28:36): ‘The LORD will bring you and your king, whom you set over you, to a nation which neither you nor your fathers have known, and there you shall serve other gods, [gods of] wood and stone.’ In summary the exile of 586 BC happened because no one heeded Deuteronomy.”⁴

After Moses summoned all Israel and gave them the Ten Commandments, the people said in response, “We will listen and obey” (Deut. 5:27). The Lord told Moses:

“I have heard the words that these people have spoken to you. Everything they have said is right. If only they had such a heart to fear me and keep all my commands always, so that they and their children would prosper forever.” (Deuteronomy 5:28–29)

The Lord’s commands weren’t meant to keep the people from experiencing a full and fruitful life, but to secure it. Moses reminded the people: “Be careful to do as the LORD your God has commanded you; you are not to turn aside to the right or the left. Follow the whole instruction the LORD your God has commanded you, so that you may live” (Deut. 5:32–33). Life was found in absolute loyalty to Him. 

Love That Shapes a Life

When Jesus was asked, “Which command in the law is the greatest?” He quoted Deuteronomy: “Love the LORD your God with all your heart, with all your soul, and with all your strength” (Deut. 6:5). Imagine how Israel’s history would have been different if they had heeded these words. 

To love the LORD means to choose Him for an intimate relationship and to obey His commands. This command, to love Him, is given often in Deuteronomy (5; 7:9; 10:12; 11:1, 13, 22; 13:3; 19:9; 30:6, 16, 20). Loving Him was to be wholehearted (with all your heart) and was to pervade every aspect of an Israelite’s being and life (soul and strength).⁵

How were they to do that practically? Deuteronomy 6 continues: “These words that I am giving you today are to be in your heart” (v. 6). The words he was referring to were all of the covenant commands Moses had communicated. To the Hebrew audience, “heart” referred more to the mind and intellect.⁶ The Israelites were to meditate on God’s words, memorizing and reflecting and recalling what He had said. 

The words of God were not only to be inscribed in their own thinking but in that of their children also. “The image is that of the engraver of a monument who takes hammer and chisel in hand and with painstaking care etches a text into the face of a solid slab of granite.”⁷

Moses told the Israelites, “Repeat them to your children. Talk about them when you sit in your house and when you walk along the road, when you lie down and when you get up” (Deut. 6:7). They were to engage in constant repetition and conversations: at home and on the go, in all situations, all day long, so that the covenant truth was the central focus of their life, reorienting every moment.

They were told to bind the words on their hands and let them be a symbol on their forehead (Deut. 6:8). Later Judaism took the commands literally (Matt. 23:5). Figuratively, the command “designates that God’s instructions were to be constant reminders to guide all their actions (suggested by ‘hand’) as well as how they viewed the world (suggested by ‘forehead’).”⁸ They were to follow God’s laws in the home (“on the doorposts of your house”) and in the community (“on your city gates”). 

“Listen, Israel,” Moses told the people, “and be careful to follow” the command—the statutes and ordinances—from the Lord. We’ve already looked ahead to see some of the ways the nation’s future was impacted when they did not heed God’s words. They didn’t wander into Babylon overnight. The drift began long before then.

“These Words Shall Be on Your Heart” 

What about us? What happens when the Lord says, “These words that I am giving you today are to be in your heart” (Deut. 6:6), and you don’t write them there? 

• When His Word is not on your heart, when you’re not actively meditating on it, you begin to forget. You still know the stories, but your love for the Lord grows thin. How can you worship the Lord with all your heart, soul, and strength when He’s never on your mind?

• When His Word is not on your hand, your obedience becomes selective. You may still say that you love God, but your daily choices are no longer intentionally shaped by what He has said. Love that never reaches your actions—and that isn’t expressed through obedience—isn’t love. It’s sentiment without surrender. 

• When His Word is not on your forehead, your perspective shifts. If Scripture isn’t defining how you see the world, you’ll start to make decisions based on others’ opinions, fear and comparison, fleeting emotions, social media, personal insecurities, and old wounds or habits. You interpret success, suffering, relationships, and your life’s purpose through a lens that places you at the center rather than Jesus.

• When His Word is not on your doorposts, the pace of life dictates what matters, and other priorities disciple your household. You’ll struggle to pass on the love of God to those in your home if the Word of God is rarely spoken within its walls. 

• When His Word is not on your gates, your faith remains private. You succumb to the temptation to soften your convictions, adjust your language, and avoid standing out. When Scripture isn’t governing your public life, your allegiance is unclear, and the world cannot tell whom you belong to. 

“Be careful,” Deuteronomy warns, not out of condemnation but because a better way is possible. A deeper love. A fuller life. A legacy that lasts. Moses wasn’t merely warning the people about what they might lose—he was inviting them, and us, to guard that which is most precious. 

Only Jesus has ever loved the Father with all His heart, soul, and strength. Where Israel failed to read and heed God’s Word, Jesus knew every line and obeyed it without wavering—the perfect King (Deut. 17:18–20). Where we have wandered from God’s ways, Jesus did not turn to the right or the left. And now, because of His mercy and grace, the Word once written in stone has been written on our hearts. 

So be careful—not in fear of losing God’s love, but because you already have it. Treasure His truth, walk in His ways, and let the Word that He’s given you be in your heart always.

^{1 Michael Rydelnik and Michael Vanlaningham, eds., The Moody Bible Commentary (Chicago: Moody Publishers, 2014), 264.
2 Michael Rydelnik and Michael Vanlaningham, eds., The Moody Bible Commentary (Chicago: Moody Publishers, 2014), 264.
3 Michael Rydelnik and Michael Vanlaningham, eds., The Moody Bible Commentary (Chicago: Moody Publishers, 2014), 264.
4 Michael Rydelnik and Michael Vanlaningham, eds., The Moody Bible Commentary (Chicago: Moody Publishers, 2014), 264.
5 Jack S. Deere, “Deuteronomy,” in The Bible Knowledge Commentary: An Exposition of the Scriptures, ed. J. F. Walvoord and R. B. Zuck, vol. 1 (Wheaton, IL: Victor Books, 1985), 274
6 Michael Rydelnik and Michael Vanlaningham, eds., The Moody Bible Commentary (Chicago: Moody Publishers, 2014), 278.
7 Eugene H. Merrill, Deuteronomy, vol. 4, The New American Commentary (Nashville: Broadman & Holman Publishers, 1994), 167.
8 Michael Rydelnik and Michael Vanlaningham, eds., The Moody Bible Commentary (Chicago: Moody Publishers, 2014), 278.}