G‑d commanded Moses to enter the Tabernacle together with Joshua. G‑d appeared to them both and informed them that a time will come when the Israelites will abandon G‑d and stray after alien gods. At that time, G‑d will hide His countenance from the nation, and they will be subjected to much evils and troubles. Therefore, G‑d says, "Write for yourselves this song, and teach it to the Children of Israel. Place it into their mouths, in order that this song will be for Me as a witness..." This 'song' is narrated in next week's Torah reading.