Each stone on the Choshen (breastplate) corresponded to a particular one of Yaakov’s twelve sons, and their names were engraved upon these stones.
Chazal say the stone called “Yoshfeh” corresponded to Binyamin, Yaakov’s youngest son. The Baal HaTurim points out that the numerical value of the word “yoshfeh” equals that of “Binyamin ben Yaakov.”
The Yerushalmi in Peah relates a very famous story about a non-Jew named Dama ben Nesina who possessed a yoshfeh stone. The sages wished to buy it for the breastplate, but when they went, the gem was hidden in a box upon which Dama’s father was sleeping.
In a remarkable display of honoring his father, he gave up the sale so as not to wake his father. This has become a paradigm in this mitzvah.
(He was rewarded in that he later had a Parah Aduma born to his cattle whose value far exceeded what he lost in not selling the stone.)
Since Binyamin had not participated in the sale of Yosef, and he had not pained his father, he was able to fulfill Kibud Av properly.
Therefore, this notable story, highlighting the lengths to which one can go to honor his father, took place with the stone that represented Binyamin.
