Ability to understand the things of God is the gift of God (compare 1 Corinthians 2:13-14); yet man is not guiltless if he lacks that ability. The people had it not because they had not felt their want of it, nor asked for it. Compare 2 Corinthians 3:14-15.

The Lord hath not given you a heart, etc. - Some critics read this verse interrogatively: And hath not God given you a heart, etc.? because they suppose that God could not reprehend them for the non-performance of a duty, when he had neither given them a mind to perceive the obligation of it, nor strength to perform it, had that obligation been known. Though this is strictly just, yet there is no need for the interrogation, as the words only imply that they had not such a heart, etc., not because God had not given them all the means of knowledge, and helps of his grace and Spirit, which were necessary; but they had not made a faithful use of their advantages, and therefore they had not that wise, loving, and obedient heart which they otherwise might have had. If they had had such a heart, it would have been God's gift, for he is the author of all good; and that they had not such a heart was a proof that they had grieved his Spirit, and abused the grace which he had afforded them to produce that gracious change, the want of which is here deplored. Hence God himself is represented as grieved because they were unchanged and disobedient: "O that there were such a heart in them, that they would fear me, and keep all my commandments always, that it might be well with them and with their children for ever!" See Deuteronomy 5:29 (note), and the note there.

Yet the Lord hath not given you an heart to perceive,.... They had some of them seen the above miracles with their bodily eyes, but had not discerned with the eyes of their understanding the power of God displayed in them, the goodness of God to them on whose behalf they were wrought, in order to obtain their deliverance, and the vengeance of God on the Egyptians for detaining them; so Jarchi interprets it of an heart to know the mercies of the Lord, and to cleave unto him:

and eyes to see, and ears to hear, unto this day; to see and observe the gracious dealings of God with them, and to hearken to his voice and obey it: so the understanding heart, the seeing eye, and hearing ear, in things spiritual, are from the Lord, are special gifts of his grace, which he bestows on some, and not on others; see Proverbs 20:12. The Targum of Jonathan is,"the Word of the Lord did not give you an heart, &c.''

Yet the LORD hath not {d} given you an heart to perceive, and eyes to see, and ears to hear, unto this day.

(d) He shows that it is not in man's power to understand the mysteries of God if it is not given to him from above.

29:4 Yet the Lord - That is, you have perceived and seen them with the eyes of your body, but not with your minds and hearts; you have not yet learned rightly to understand the word and works of God, so as to know them for your good, and to make a right use of them, and to comply with them: which he expresseth thus, the Lord hath not given you, and c. not to excuse their wickedness, but to direct them to whom they must have recourse for a good understanding of God's works; and to intimate that although the hearing ear, and the seeing eye, be the workmanship of God, yet their want of his grace was their own fault, and the just punishment of their former sins; their present case being like theirs in Isaiah's time, who first shut their own eyes and ears that they might not see and hear, and would not understand, and then by the righteous judgment of God, had their eyes and ears closed that they should not see and hear, and understand. God's readiness to do us good in other things, is a plain evidence, that if we have not grace, that best of gifts, 'tis our own fault and not his: he would have gathered us, and we would not.

29:1-9 Both former mercies, and fresh mercies, should be thought on by us as motives to obedience. The hearing ear, and seeing eye, and the understanding heart, are the gift of God. All that have them, have them from him. God gives not only food and raiment, but wealth and large possessions, to many to whom he does not give grace. Many enjoy the gifts, who have not hearts to perceive the Giver, nor the true design and use of the gifts. We are bound, in gratitude and interest, as well as in duty and faithfulness, to keep the words of the covenant.