John Chrysostom

And the reason why He says that this is the work of God is, that He may show that he who is put into this path by God, has much need of grace; from which it is proved, that great is the reward of those rich men, who are willing to follow the 1discipline of Christ.

Catena Aurea by Aquinas ↗

Theophylact of Ohrid

But with God this is possible. Christ said: "Make friends for yourselves by means of unrighteous wealth" (Lk. 16:9). Do you see how all things become possible when we hear the Word of God? "With men this is impossible," that is, it is impossible when we reason in human terms. Some are puzzled how Christ said that "all things are possible with God." Can He then also sin? …

Commentary on Mark ↗

Clement of Alexandria

But the Lord replies, "Because what is impossible with men is possible with God." This again is full of great wisdom. For a man by himself working and toiling at freedom from passion achieves nothing. But if he plainly shows himself very desirous and earnest about this, he attains it by the addition of the power of God. For God conspires with willing souls. But if they abandon their eagerness, the spirit which is bestowed by God is also restrained. …

Who is the Rich Man that Shall Be Saved? ↗

Bede

And Jesus, looking at them, said, "With men it is impossible, but not with God. For all things are possible with God." It is not to be understood that the greedy and proud, who were signified by the name of that rich man, will enter the kingdom of heaven with their greed and pride: but it is possible for God, that through His word, as we see both to have been done and to be done daily, that they are converted from the greed for temporal things to the love of eternal things, and from pernicious pride to salutary humility.

On the Gospel of Mark ↗