Passage
Now therefore write you this canticle, and teach the children of Israel: that they may know it by heart, and sing it by mouth, and this song may be unto me for a testimony among the children of Israel.
Now therefore write you this canticle, and teach the children of Israel: that they may know it by heart, and sing it by mouth, and this song may be unto me for a testimony among the children of Israel.
Deuteronomy 31:17 And my wrath shall be kindled against them in that day: and I will forsake them, and will hide my face from them, and they shall be devoured: all evils and afflictions shall find them, so that they shall say in that day: In truth it is because God is not with me, that these evils have found me.
Deuteronomy 31:18 But I will hide, and cover my face in that day, for all the evils which they have done, because they have followed strange gods.
Deuteronomy 31:19 Now therefore write you this canticle, and teach the children of Israel: that they may know it by heart, and sing it by mouth, and this song may be unto me for a testimony among the children of Israel.
Deuteronomy 31:20 For I will bring them into the land, for which I swore to their fathers, that floweth with milk and honey. And when they have eaten, and are full and fat, they will turn away after strange gods, and will serve them: and will despise me, and make void my covenant.
Deuteronomy 31:21 And after many evils and afflictions shall have come upon them, this canticle shall answer them for a testimony, which no oblivion shall take away out of the mouth of their seed. For I know their thoughts, and what they are about to do this day, before that I bring them into the land which I have promised them.
The verse centers on "therefore", "write", "canticle", "teach", "children", "israel", "heart", and "sing". It is saying that the verse draws attention to "therefore" and "write", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 18's "But I will hide and cover my..." into verse 20's "For I will bring them into the...", so "therefore" and "write" belong inside that flow. In Deuteronomy context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "therefore" and "write" with trust shaped by these words, not by a vague optimism outside the passage.