Ambrose of Milan

But riches in themselves are not blameable. For the ransom of a man's life are his riches, for he who gives to the poor, redeems his soul. There is therefore scope for virtue even in these material riches. Ye are as it were pilots, in a great sea. If any man steers well his ship, he quickly passes over the sea, and reaches his haven, but he who cannot manage his property is sunk together with his burthen. Wherefore it is written, The rich man's strength is his strong city.

Letters 61-70 ↗

Bede

The wealth of the rich is his strong city, etc. The rich trust in their wealth as in a fortified city; the poor therefore tremble, fearing they may lack because they know they are needy. Spiritually, he who is rich in God trusts in Him through good works, as in an impregnable city that no enemy can overcome; but those who are afflicted by a lack of virtues are therefore in need of heavenly riches because they fear with harmful dread to endure harsh labors for the Lord.

Commentary on Proverbs ↗