Albert Barnes Commentary Mark 10:24

"And the disciples were amazed at his words. But Jesus answereth again, and saith unto them, Children, how hard is it for them that trust in riches to enter into the kingdom of God!" — Mark 10:24 (ASV)

Children. An expression of affection, perhaps also implying a reproof that their slowness of understanding was like children. When they should have seen at once the truth of what he said, they were slow to learn it. It became necessary, therefore, to repeat what he had said.

How hard. With how much difficulty.