Psalm 45:6 Your throne, O God, will last forever and ever; a scepter of justice will be the scepter of your kingdom.

Righteousness and justice are the two things that appear over and over again in descriptions of a reign that is pleasing to God. A king who is righteous and just, providing for widows and orphans and resident aliens, can expect to be blessed in his rule. The kings of Israel knew this, it’s just hard to do.