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.
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.
Deuteronomy 31:22 Moses therefore wrote the canticle, and taught it to the children of Israel.
Deuteronomy 31:23 And the Lord commanded Josue the son of Nun, and said: Take courage, and be valiant: for thou shalt bring the children of Israel into the land which I have promised, and I will be with thee.
The verse centers on "after", "evils", "afflictions", "shall", "come", "upon", and "canticle". It is saying that the verse draws attention to "after" and "evils", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 20's "For I will bring them into the..." into verse 22's "Moses therefore wrote the canticle and taught...", so "after" and "evils" 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 "after" and "evils" with trust shaped by these words, not by a vague optimism outside the passage.