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.

Wesley's Notes

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.

Matthew Henry's Concise Commentary

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.