And it shall be, if thou do at all forget the Lord thy God,.... Either the mercies they received from him, not acknowledging they came from him, but ascribing them to themselves; or their duty to him, to whom they were so greatly obliged: and walk after other gods, and serve them, and worship them; which would be to forget him indeed, forsaking his worship, and giving homage and adoration to idols, which is what is intended by these expressions:

I testify against you this day that ye shall surely perish; by one judgment and calamity or another, as the sword, famine, pestilence, and captivity; there being nothing more provoking to God than idolatry, which so much detracts from his honour and glory: and which besides, in such a people, so highly favoured of God, it argued the basest ingratitude.

To strengthen his admonition, Moses pointed again in conclusion, as he had already done in Deuteronomy 6:14 (cf. Deuteronomy 4:25.), to the destruction which would come upon Israel through apostasy from its God.

And it shall be, if thou do at all forget the LORD thy God, and walk after other gods, and serve them, and worship them, I {k} testify against you this day that ye shall surely perish.

(k) Or take to witness the heaven and the earth, as in De 4:26.

8:10-20 Moses directs to the duty of a prosperous condition. Let them always remember their Benefactor. In everything we must give thanks. Moses arms them against the temptations of a prosperous condition. When men possess large estates, or are engaged in profitable business, they find the temptation to pride, forgetfulness of God, and carnal-mindedness, very strong; and they are anxious and troubled about many things. In this the believing poor have the advantage; they more easily perceive their supplies coming from the Lord in answer to the prayer of faith; and, strange as it may seem, they find less difficulty in simply trusting him for daily bread. They taste a sweetness therein, which is generally unknown to the rich, while they are also freed from many of their temptations. Forget not God's former dealings with thee. Here is the great secret of Divine Providence. Infinite wisdom and goodness are the source of all the changes and trials believers experience. Israel had many bitter trials, but it was to do them good. Pride is natural to the human heart. Would one suppose that such a people, after their slavery at the brick-kilns, should need the thorns of the wilderness to humble them? But such is man! And they were proved that they might be humbled. None of us live a single week without giving proofs of our weakness, folly, and depravity. To broken-hearted souls alone the Saviour is precious indeed. Nothing can render the most suitable outward and inward trials effectual, but the power of the Spirit of God. See here how God's giving and our getting are reconciled, and apply it to spiritual wealth. All God's gifts are in pursuance of his promises. Moses repeats the warning he had often given of the fatal consequences of forsaking God. Those who follow others in sin, will follow them to destruction. If we do as sinners do, we must expect to fare as sinners fare.