In Isaiah 1:3, Israel's lack of understanding parallels this verse: both depict God's people seeing or knowing yet failing to respond.

In Isaiah 48:6-8, God says they never heard or knew new things—same failure to perceive what is shown.

Isaiah 48:8 repeats the charge of not hearing and having ears closed—directly parallel language about spiritual deafness.

In Isaiah 58:2, people seek God outwardly but lack true obedience—parallel to seeing without observing, hearing without obeying.

In Deuteronomy 4:9, Moses warns not to forget what eyes have seen—reinforcing the danger of seeing without internalizing.

In Deuteronomy 29:2-4, Moses says they saw great wonders yet were not given hearts to understand—direct parallel to failing to perceive.

In Nehemiah 9:10-17, the people saw God's signs in Egypt but acted rebelliously—same pattern of sight without faithful response.

In Psalm 106:7-13, the fathers did not consider God's wondrous works and soon forgot them—echoing the failure to observe.

In Numbers 14:22, the generation saw God's glory and signs yet tested Him—they saw but did not obey.

Acts 28:22-27 quotes Isaiah 6:9-10 on hearing without understanding—same theme of spiritual blindness, though not a direct citation of 42:20.

Ezekiel 33:31 describes people who hear words but do not act—direct parallel to seeing and hearing yet not perceiving or obeying.

In John 9:37-40, Jesus confronts Pharisees who see yet remain blind—fulfilling the same spiritual dullness.

Ezekiel 12:2 uses the identical phrase 'eyes to see but do not see, ears to hear but do not hear'—a direct parallel.

In Acts 28:26, Paul quotes 'hear but not understand' — matching the unobservant observer of Isaiah 42:20.

In John 12:40, God blinds eyes and hardens hearts — a stronger version of the spiritual deafness seen in Isaiah 42:20.

In Mark 11:33, the leaders say 'We cannot tell' — like Isaiah's observer who opens ears but hears not.

In Luke 20:7, they answer 'They could not tell' — mirroring the willful blindness of Isaiah 42:20.

In Matthew 21:27, the religious leaders refuse to answer Jesus — echoing the blind observer who sees but does not perceive.

Jeremiah 4:22 describes foolish people who lack understanding—parallel to seeing but not discerning, hearing but not knowing.

In Psalm 107:43, the wise are called to attend and consider—contrasting the unobservant described here.