Theophylact of Ohrid

It is not wealth in itself that is evil, but those who hoard it are evil and worthy of condemnation, for one ought not to have it, that is, to keep it for oneself, but to put it to good use. It is called wealth precisely because it is meant for beneficial use, not for hoarding. Therefore it is difficult for those who hoard and lock it away to "enter the Kingdom of God." And the word "difficult" here means the same as impossible. It is indeed exceedingly difficult for a rich man to be saved.

Commentary on Mark ↗

Clement of Alexandria

Let this teach the prosperous that they are not to neglect their own salvation, as if they had been already foredoomed, nor, on the other hand, to cast wealth into the sea, or condemn it as a traitor and an enemy to life, but learn in what way and how to use wealth and obtain life.

Who is the Rich Man that Shall Be Saved? ↗

Augustine of Hippo

Such, O my soul, are the miseries that attend on riches. They are gained with toil and kept with fear. They are enjoyed with danger and lost with grief. It is hard to be saved if we have them; and impossible if we love them; and scarcely can we have them, but we shall love them inordinately. Teach us, O Lord, this difficult lesson: to manage conscientiously the goods we possess, and not covetously desire more than you give to us.

Letter 203 ↗

Bede

And looking around, Jesus said to His disciples: How difficult it is for those who have riches to enter the kingdom, etc. It is clear indeed that those who strive here to multiply riches neglect to seek the joys of another life: but there is much difference between having and loving riches. Many indeed, having them, do not love; many, not having them, love. Similarly, others both have and love. …

On the Gospel of Mark ↗