15 And further, after giving this admonition, “not to be high-minded,” he also taught the manner in which they would be able to avoid being so. And how was it? That they should consider the nature of wealth, how uncertain and faithless it is! Therefore he goes on to say, “Neither trust in uncertain riches.” The rich man is not one who is in possession of much, but one who gives much. Abraham was rich, but he was not covetous; for he turned not his thoughts to the house of this man, nor prayed into the wealth of that man; but going forth he looked around wherever there chanced to be a stranger, or a poor man, in order that he might succour poverty, and hospitably entertain the traveller.
He covered not his roof with gold, but fixing his tent near the oak, he was contented with the shadow of its leaves. Yet so illustrious was his lodging, that angels were not ashamed to tarry with him; for they sought not splendour of abode, but virtue of soul. This man then let us imitate, beloved, and bestow what we have upon the needy. That lodging was rudely prepared, but it was more illustrious than the halls of kings. No king has ever entertained angels; but he, dwelling under that oak, and having but pitched a tent, was thought worthy of that honour: not receiving the honour on account of the meanness of his dwelling, but enjoying that benefit on account of the magnificence of his soul, and the wealth therein deposited.
Source: Homilies on the Statues (New Advent)