“And Melchizedek king of Salem brought forth bread and wine and he was the kohein (priest) of El (G-d) the Most High.” – Genesis 14:18
“Five possessions did the Holy Blessed One, set aside as his own in this world, and these are they: The Torah, one possession; Heaven and earth, another possession; Abraham, another possession; Israel, another possession; The Temple, another possession.” – Avos 6:9, sefaria.org
“G-d acquired these five possessions to serve as the instruments by means of which He can bestow His kindness and generosity on man, to let him rise to the lofty position of comprehending His greatness.” – Akeidat Yitzchak, sefaria.org
A tenth of all that Abraham retrieved from the five kings was given to Melchizedek; the remainder was considered properly tithed from the perspective of a later Torah injunction; yet, Abraham kept none of this, for his reward has to do with heaven and earth. Therefore, what has any man to offer Abraham? The King of Sodom’s riches would have been devoid of any spiritual blessing, since they would not have been bestowed upon Abraham by G-d; but, rather by man.
While it is true that blessings can be given to someone through men, according to G-d’s design, this would not have been the case, in regard to the loot that was recovered by Abraham, when rescued his nephew Lot, who was captured by the five kings. Why? Because Abraham was righteous, and “disdained profit gained through oppression” (Akeidas Yitzchak; sefaria.org). That is to say, that he forsook the wealth that was rightly his according to custom in order to maintain his integrity.
Every now and then, we may find ourselves in a similar position, not necessarily having to do with possessions; rather, as pertaining to a challenge designed to test the integrity of our convictions. Our belief and practice, as well as the strength of our convictions must be tested, so that we are able to permit these to take root in actuality. The tests designed for Abraham, throughout the narrative of his life, as recorded in Torah, may also be understood this way.
“The L-RD trieth the righteous.” – Psalms 11:5, JPS 1917 Tanach
The Tree of Life 