John Chrysostom

But the Lord said this to His disciples, who were poor and possessed nothing, in order to teach them not to blush at their poverty, and as it were to make an excuse to them, and give them a reason, why He had not allowed them to possess any thing. It goes on: And the disciples were astonished at his words; for it is plain, since they themselves were poor, that they were anxious for the salvation of others.

Catena Aurea by Aquinas ↗

Bede

Little children, how difficult it is for those who trust in riches to enter the kingdom of God. Where it must be noted that he did not say, how impossible, but how difficult it is. For what is impossible cannot be done at all. What is difficult can be done with toil. …

On the Gospel of Mark ↗