In Deuteronomy 31:21, the song's purpose is explained: it will testify against Israel when they fall into sin, elaborating on the command to write it.

Deuteronomy 31:22 immediately records Moses obeying the command to write and teach the song, fulfilling the instruction given in verse 19.

In Deuteronomy 31:26, the Book of the Law is placed beside the ark as a witness—same function as the song, both written witnesses against Israel.

Deuteronomy 31:30 shows Moses speaking the song to all Israel, carrying out the command to 'put it in their mouths' from verse 19.

Deuteronomy 32:1-43 is the actual song Moses wrote, providing the full content of the witness commanded in verse 19.

Deuteronomy 32:44 records Moses reciting the song—the direct fulfillment of the command to write and teach it.

Deuteronomy 32:45 shows Moses finishing the song—the conclusion of the instruction in 31:19.

In Numbers 17:10, Aaron's rod is kept as a sign against rebels—parallel to the song as a witness against rebellious Israel.

In Joshua 24:27, a stone is set as a witness against the people—parallel to the song as a witness; both are physical witnesses.

2 Peter 1:15 shows Peter ensuring a written reminder after his death, mirroring Moses' song as a lasting witness.

Isaiah 30:8 commands writing on a tablet for future witness — directly parallels the command to write the song as a testimony.

Jeremiah 30:2 commands writing God's words in a book — directly parallels the command to write the song as a record.

In Jeremiah 1:9, God touches Jeremiah's mouth and puts words in it—parallel to the song's words being put in Israel's mouth as a witness.

Revelation 1:11 commands John to write what he sees to the churches, similar to Moses writing the song for teaching.

In Genesis 31:44, Jacob and Laban set a heap as a witness to their covenant—parallel to the song as a witness between God and Israel.

Habakkuk 2:2 also commands writing for a witness—a vision to be made plain—echoing the song as a testimony.

In Ezekiel 2:5, the prophet is sent as a witness to a rebellious house—parallel to the song serving as a witness against rebellious Israel.

In Psalm 102:18, writing is for future generations to praise God — parallels the song's purpose as a witness for later times.

In Psalm 50:7, God testifies against Israel — echoing the witness role of the song in Deuteronomy.

In Esther 9:20, Mordecai writes letters to establish Purim — a parallel act of writing for remembrance and witness.