What does Luke 9:44 mean?

Luke has just mentioned the amazement of the crowd. They are stunned, both by Jesus' deliverance of the possessed boy and by His overall miraculous ministry (Luke 9:43). With that praise still on their minds, the disciples hear Jesus talk of His coming betrayal and death. Mark explains that this is an on-going conversation as they travel through Galilee (Mark 9:30). Luke condenses the events to reveal the startling realization the disciples experience. They witness Jesus' glory and power and then hear Jewish leaders will murder Him.

Now, men praise Jesus. Soon, they will kill Him. Judas will betray Him. Peter will deny Him. An unidentified mob will be manipulated into ordering His execution. The civil government tasked with upholding justice will crucify an innocent Man. And the religious leaders will knowingly plan the destruction of the Messiah (Luke 22—23).

Luke alone records Jesus telling the disciples to let His words "sink into your ears." Jesus is reinforcing God's words to Peter, James, and John on the Mount of Transfiguration: "This is my Son, my Chosen One; listen to him" (Luke 9:35). The sentiment is not unlike the seeds that fall into the good soil "and grew and yielded a hundredfold" (Luke 8:8). If the disciples would allow Jesus' warning to penetrate their understanding, they could use the time for great good.

Instead, Luke explains the meaning was "concealed from them" (Luke 9:45). The text isn't clear as to who or what is doing the concealing. Some think it is the Holy Spirit. Others believe that since the disciples earlier refused to believe the Messiah could die (Luke 9:21–22; Matthew 16:21–23; Mark 8:31–33), they veiled their own hearts from the truth.