Matthew Poole and continuators on Deuteronomy 29:29

29 The secret things belong unto the LORD our God : but those things which are revealed, belong unto us, and to our children for ever, that we may do all the words of this law.

Having now mentioned the dreadful and amazing judgments of God upon the whole land and people of Israel, and foreseeing by the spirit of prophecy the utter extirpation and destruction which would come upon them for their wickedness, he breaks out into this pathetical exclamation either to bridle their curiosity, who hearing this, would be apt to enquire into the time and manner of so great an event, or to quiet his own mind, and satisfie the scruples of others, who perceiving God to deal so severely with his own people, when in the mean time he suffered those Nations which were guilty of grosser Atheisme and Idolatry, and Impiety than the generality of the Jewish people were to live and prosper in the world, might thence take occasion to deny or reproach his providence, or question the equity of his proceedings. To this he answers, that the ways and judgments of God, though never unjust, are ofttimes secret and hidden from us, and unsearchable by our shallow capacities, and are matter for our admiration, not for our enquiry.

But the things which are revealed by God and his word, these are the proper object of our enquiries and studies, that thereby we may come to the knowledge of our duty by the practise whereof we may be kept from such terrible punishments and calamities as these now mentioned.