Seeing many things, but thou observest not; opening the ears, but he heareth not.

Wesley's Notes

42:20 Heareth not - Thou dost not seriously consider the plain word, and the wonderful works of God.

Jamieson-Fausset-Brown Bible Commentary

20. observest-Thou dost not keep them. The "many things" are the many proofs which all along from the first God had given Israel of His goodness and His power (De 4:32-38; 29:2-4; Ps 78:1-72; 105:1-45).

he-transition from the second to the third person. "Opening . ears," that is, though he (Israel) hath his ears open (see on [785]Isa 6:10). This language, too (see on [786]Isa 42:19), applies to Messiah as Jehovah's servant (Isa 50:5; Ps 40:6).

Matthew Henry's Concise Commentary

42:18-25 Observe the call given to this people, and the character given of them. Multitudes are ruined for want of observing that which they cannot but see; they perish, not through ignorance, but carelessness. The Lord is well-pleased in the making known his own righteousness. For their sins they were spoiled of all their possessions. This fully came to pass in the destruction of the Jewish nation. There is no resisting, nor escaping God's anger. See the mischief sin makes; it provokes God to anger. And those not humbled by lesser judgments, must expect greater. Alas! how many professed Christians are blind as the benighted heathen! While the Lord is well-pleased in saving sinners through the righteousness of Christ he will also glorify his justice, by punishing all proud despisers. Seeing God has poured out his wrath on his once-favoured people, because of their sins, let us fear, lest a promise being left us of entering into his rest, any of us should be found to come short of it.