פּירוש אויף שמות 28:17

ומלאת בו AND THOU SHALT FILL IT [WITH FILLINGS OF STONES] — Because the stones fill the hollows of the settings which were specially made for them it calls them by the term מלואים “fillings”.

אדם, a “carnelian;”

And you shall set it with settings of stones, four rows of stones. And in each row, three precious stones, for a court of law [beit din] must have no less than three [judges]. And they shall shine like the radiance of these stones, for they are noble stones that appear [as pure] inside as they do outside. And in the Akeidah [Rabbi Yitzchak Arama’s commentary], he wrote that these stones were some expensive and some inexpensive, to hint that a judge should treat a case involving a single coin with the same justice as one involving a hundred maneh. And the names of the tribes were engraved upon them according to their birth order, to hint that one should not show favoritism to any person, but should hear the small and the great alike, as if there is no advantage to the greatest of the tribes over the smallest, except for the birth order based on age, and apart from this, all are equal. This is a proper hint, and it also hints to the judge not to become haughty saying, “I will rule,” for one whose heart is arrogant in rendering decisions is a fool, wicked, and coarse-spirited. And the verse states, He guides the humble in justice (Psalms 25:9). And the reason for this we explained above in Parashat Mishpatim. And this is why they said (Talmud Shabbat 139a) that in the merit of and he will see you and rejoice in his heart, Aaron earned the breastplate of judgment upon the heart, for because of his great humility, he did not envy the authority of Moses, his brother who was younger than him in birth order. He merited the breastplate of judgment, which depends on the attribute of humility, and the names of the tribes were written there according to their birth order, and this is precisely measure for measure.