Adam Clarke on Matthew 13:15

Heart is waxed gross - Επαχυνθη, is become fat - inattentive stupid, insensible. They hear heavily with their ears - are half asleep while the salvation of God is preached unto them.

Their eyes they have closed - Totally and obstinately resisted the truth of God, and shut their eyes against the light.

Lest - they should see, etc. - Lest they should see their lost estate, and be obliged to turn unto God, and seek his salvation. His state is truly deplorable who is sick unto death, and yet is afraid of being cured. The fault is here totally in the people, and not at all in that God whose name is Mercy and whose nature is love.