Commentaire sur Les Psaumes 68:28

There Benjamin the youngest became the ruler over them.

rules over them Heb. רֹדֵם, like רֹדָם, with a “kamatz.” From there, he merited to become king because he descended first into the sea, and so did Samuel say to Saul (I Sam. 15:17): “Even if you are small in your own eyes, are you not the head of the tribes of Israel?” which Jonathan paraphrases: The tribe of Benjamin crossed the sea at the head of all the other tribes.

the princes of Judah pelt them with stones They envy them and throw stones at them, and so do the princes of Zebulun and the princes of Naftali. So, he says to him, “Your God has commanded your strength.” Another explanation: רִגְמָתָם is the equivalent of רִקְמָתָם, their embroidery, their embroidered garments, an expression of purple (ארגמן). In this way Menachem associated it (p. 161).