Deuteronomy 31:21 Meaning and Explanation
“And it shall come to pass, when many evils and troubles are befallen them, that this song shall testify against them as a witness; for it shall not be forgotten out of the mouths of their seed: for I know their imagination which they go about, even now, before I have brought them into the land which I sware.”
King James Version (KJV)
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Read Full Chapter →Memory can preserve words long after a community has drifted from their meaning. Deuteronomy 31:21 matters because God places his warning in Israel's mouth before they enter a rich land and before their later turning away. The verse joins divine foreknowledge, human accountability, suffering, family memory, and the enduring power of a song taught to a people.
God appoints the song Moses is about to teach Israel as a lasting witness. When covenant unfaithfulness brings troubles, the remembered song will expose the truth of what God had already warned and known.
The Context of Deuteronomy 31:21
Moses is nearing death on the plains east of Jordan, and Joshua has received his public charge. Earlier in the chapter Moses wrote the law and ordered its regular public reading before men, women, children, and strangers within Israel's gates. At the tabernacle, the LORD tells Moses that Israel will later forsake the covenant after entering the promised land and enjoying its abundance. Therefore Moses and Joshua are commanded to write and teach a song. Verse 21 gives the reason for that song's preservation. The next verse records Moses writing it that same day, and chapter 32 contains the song itself.
What Does Deuteronomy 31:21 Mean?
The verse looks ahead to a time when "many evils and troubles" have befallen Israel. These troubles stand within the warning already given in verses 16-20: Israel will turn to other gods, break the covenant, and experience the consequences of that rebellion. In that hour, "this song" will testify "as a witness." A witness speaks to what is true. The song will recall God's covenant faithfulness, Israel's calling, and the people's departure from him. Its testimony does not arise from a later accusation shaped by hardship. God had caused the warning to be written and taught before Israel crossed into the land.
The phrase "it shall not be forgotten out of the mouths of their seed" gives the song a communal and generational place. It is to be learned, spoken, and passed on. Earlier, Moses had required the gathering of children so they might hear and learn to fear the LORD. The song therefore belongs alongside the written law as a means by which Israel remembers its God-given history and obligations. The chapter does not present Israel's future failure as an excuse for it. God's knowledge of their "imagination," their developing inward purpose and course, shows that he sees the direction they are already taking even before the promised land is given.
This verse prepares for the song of Moses in the following chapter, where heaven and earth are summoned to hear and where God's righteousness is set against Israel's corruption. The song's witness is severe because covenant life with God is serious, yet its preservation also keeps God's words within the people's hearing. Scripture repeatedly shows God calling his people back through remembered words, public reading, prayer, and song. In the New Testament, the victorious worshipers are described as singing "the song of Moses the servant of God." That later scene confirms that the song of Moses belongs to the Bible's enduring testimony to God's righteous works and faithful rule.
Bible Verses Related to Deuteronomy 31:21
“Now therefore write ye this song for you, and teach it the children of Israel: put it in their mouths, that this song may be a witness for me against the children of Israel.”
- Deuteronomy 31:19
“Give ear, O ye heavens, and I will speak; and hear, O earth, the words of my mouth.”
- Deuteronomy 32:1
“For he established a testimony in Jacob, and appointed a law in Israel, which he commanded our fathers, that they should make them known to their children:”
- Psalm 78:5
“And they sing the song of Moses the servant of God, and the song of the Lamb, saying, Great and marvellous are thy works, Lord God Almighty; just and true are thy ways, thou King of saints.”
- Revelation 15:3
Where Deuteronomy 31:21 Echoes in Scripture
Revelation 15:3 explicitly names "the song of Moses the servant of God" as the song sung by those who stand victorious before God. The reference reaches back to the song Moses teaches in Deuteronomy 31 and speaks in chapter 32. In Deuteronomy, the song witnesses against covenant rebellion. In Revelation, a song associated with Moses accompanies praise for God's works and ways. Together these passages show that God's remembered acts call forth both truthful witness and worship.
How to Apply Deuteronomy 31:21 Today
This verse invites households and congregations to give God's words a durable place in shared memory. Reading, singing, reciting, and discussing Scripture can remain with us when prosperity, pressure, or sorrow exposes where our hearts have been leaning. When trouble comes, remembered words can help us examine ourselves honestly before God rather than treating hardship as meaningless. Parents, grandparents, teachers, and friends can pass on more than information by helping the next generation speak God's truth aloud. Such practices cultivate a memory that is available for repentance, gratitude, and faithful return.
Reflection & Prayer
What words of Scripture have been placed in our mouths often enough to guide us when life becomes difficult? We may also ask whether our habits are forming a memory of God's covenant faithfulness in those entrusted to our care. Suggested prayer: "Lord, write your true words deeply among us. Give us humble hearts when they expose us, and keep our households ready to remember and return to you."