"Scripture (Psalms 101:6) says: 'My eyes are upon the faithful of the land (ne'emnei eretz), that they may dwell with Me.'
What is ne'eman (faithful)?
In Pirkei Avot (6:1) it says that the Torah makes a person 'righteous, pious, upright and faithful' (tzaddik, hassid, yashar ve-ne'eman).
According to the common, everyday usage of these terms, it seems that we have here a list in a descending order.
Closer examination, however, shows that the opposite is true: it is clearly an ascending order.
A righteous person (tzaddik) is not an ordinary human being; he is a person who is on the level of always doing what is right, in the religious as well as all other spheres of life.
'Pious' (hassid) is one level higher: a person who not only follows the Halacha meticulously but also goes beyond the boundaries of what is prescribed by law, both practically and emotionally.
While the first two epithets are usually used in the religious sphere, the next one, 'upright' (or 'honest,' yashar), seems broader.
In this context, however, it has a specific meaning:
It does not designate a person who is not a crook, but rather a person with a straight heart, one whose inner being is not convoluted.
It is the quality of having a pure heart which does not look for nor finds complexities, but always goes directly in the right way.
Indeed, in the Book of Psalms (97:11), the 'upright of heart' (yishrei lev) are placed above the "righteous" (tzaddikim), because it is such a rare quality.
It is not simplicity born of ignorance, but the ability to know and understand problems and complexities - and yet remain simple.
The last epithet, 'faithful' (ne'eman), also has a specific meaning here.
It is not only the sort of a person one can entrust one's money with, but the quality of total faithfulness, complete devotion.
In fact, in the entire Bible there is only one person who is given this title: Moses (see Numbers 12:7)."
From a eulogy in memory of Michael Fox, by Rabbi Adin Steinsaltz