American Standard Version
And it shall come to pass, when many evils and troubles are come upon them, that this song shall testify before them as a witness; for it shall not be forgotten out of the mouths of their seed: for I know their imagination which they frame this day, before I have brought them into the land which I sware.

Berean Study Bible
And when many troubles and afflictions have come upon them, this song will testify against them, because it will not be forgotten from the lips of their descendants. For I know their inclination, even before I bring them into the land that I swore to give them.”

Douay-Rheims Bible
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 de this day, before that I bring them into the land which I have promised them.

English Revised Version
And it shall come to pass, when many evils and troubles are come upon them, that this song shall testify before 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 Bible
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.

World English Bible
It shall happen, when many evils and troubles are come on them, that this song shall testify before them as a witness; for it shall not be forgotten out of the mouths of their seed: for I know their imagination which they frame this day, before I have brought them into the land which I swore."

Young's Literal Translation
'And it hath been, when many evils and distresses do meet it, that this song hath testified to its face for a witness; for it is not forgotten out of the mouth of its seed, for I have known its imagining which it is doing to-day, before I bring them in unto the land of which I have sworn.'

Deuteronomy 31:21 Additional Translations ...