Read Deuteronomy 32
“Now write down for yourselves this song and teach it to the Israelites and have them sing it, so that it may be a witness for me against them” (Dt. 31:19).
God had given Moses a song to sing. He’d given it to Joshua, too. So the Israelites would have proof of God’s truth, evidence that Almighty God does not go back on His Word.
He wanted the Israelites to know the song so well that when the consequences hit from the forsaking they would soon commit, they might hear it in the background and remember that God, the LORD, is always faithful, always true. Perhaps they would hear someone whistling the tune as they contemplated the surrounding destruction, the consequences of their betrayal of the God who had delivered them exactly what He’d promised. Maybe they would hear the tune and their thoughts would go something like this:
“He is the Rock, his works are perfect, and all his ways are just” (v4).
So don’t blame Him when you turn aside from the Law of life that He has so carefully given.
“Ask your father and he will tell you, your elders, and they will explain to you” (v7).
Take a look at history, and you will see all that God has done for His children. All the promises He has made. All the forsaking He has endured. And every time His people forsake Him, He always, always deals swiftly and justly. For He is the One God who alone is worthy of your faithful service. He warned them, just as He warned you, trouble will come on you if you fail to follow His ways. But know this, Israel, and do not forget: your God is The God of All That Is. He alone is the Rock. (See v31, 39.)
When Moses and Joshua taught the children of God this song, they gave them truth for an eternal purpose. They gave them solid reminding of the One they serve. The gave them the very Word of God to keep always around, always at the center of life itself. So when Israel forgot God, they could remember the song that Moses gave them about real living. And then they could turn back to that same Almighty God who is not only just, but equally gracious.