And might not be as their fathers - Their ancestors, particularly in the wilderness, as they passed through it to the promised land. See Exodus 32:7-9; Exodus 33:3; Exodus 34:9; Acts 7:51-53.
A stubborn and rebellious generation - Stiff-necked, ungovernable; inclined to revolt. Nothing was more remarkable in their early history than this.
A generation that set not their heart aright - Margin, as in Hebrew, “prepared not their heart.” That is, they took no pains to keep their heart aright, or to cherish right feelings toward God. They yielded to any sudden impulse of passion, even when it led them to revolt against God. This is as true of sinners now as it was of them, that they “take no pains” to have their hearts right with God. If they did, there would be no difficulty in doing it. It is not with them “an object of desire” to have their hearts right with God, and hence, nothing is more easy or natural than that they should rebel and go astray.
And whose spirit was not stedfast with God - That is, they themselves did not maintain a firm trust in God. They yielded readily to every impulse, and every passion, even when it tended to draw them away wholly from him. There was no such “strength” of attachment to him as would lead them to resist temptation, and they easily fell into the sin of idolatry.