…the ability to comprehend spiritual truth is a gracious gift of God, sovereignly bestowed upon the elect (v. 11). The reprobate ones, on the other hand, are passed over. They reap the natural consequence of their own unbelief and rebellion – spiritual blindness (v. 13).*

See Isaiah 6:9&10

*NKJV McArthur Study Bible notes on Matthew 13:10-15