Deuteronomy 31:20-22

International Standard Version

²⁰ because after I’ve brought them to the land flowing with milk and honey that I promised to their ancestors by an oath, they’ll eat, grow fat, and then they’ll turn to other gods and serve them, while despising me and breaking my covenant. ²¹ Then, when many evils and troubles will have come upon them, this song will serve as a witness against them, since their descendants won’t fail to sing it. I know the plan that they are devising even before I bring them into the land that I promised them^[a] by an oath.”

²² So Moses wrote the song that very day and taught it to the Israelis.