http://revach.net/article.php?id=4969

Section: Parshas HaShavua   Category: Quick Vort
Parshas Titzaveh: Meshech Chochma - Dama Ben Nesina Is Immortalized Through Binyomin's Stone
Chazal tell us that one time the Avnei Yashfei from the Choshen were lost. The Chachomim located one in Ashkelon in the possession of a Dama ben Nesina. We all know the story how they wanted to buy it, but Dama would not wake his father up to sell it. This story is the paramount example of Kibud Av VaEim.

The Meshech Chochma says that it is no coincindence that the lesson of Kibbud Av VaEim is learned through the Avnei Yashfei. Each stone had engraved on it the name of one Shevet. Teh Yashfei was the stone of Binyomin. Binyomin was the only one of the Shevatim that did not cause his father grief in the story of Yosef's mechira. All the other Shevatim did not reveal the truth because of a Cheirem that that they agreed to (including Hashem, Yitzchok, and Yosef).

Binyomin did not know about the Mechira and thus did not withhold any information from Yaakov. Since his Kibud Av was complete, the great lesson was learned from his stone.