The Mekhilta reinforces Rabbi Tarfon's teaching about the tribe of Judah with a verse from Psalms. "When Israel went out of Egypt, the house of Jacob from the people of a foreign tongue, Judah was His holy one, Israel His ruler" (Psalms 114:1-2). The verse places Judah in a position of sanctity — "His holy one" — ahead of all the other tribes. Why? Because Judah sanctified God's name at the sea.
The phrase "His holy one" points back to the moment when Nachshon ben Aminadav and his tribe leapt into the crashing waves before the waters had parted. That act of raw faith was not merely brave — it was an act of kiddush (the sanctification blessing over wine) Hashem, the sanctification of God's name before the entire nation. While the other tribes argued and hesitated, Judah demonstrated through action that God could be trusted absolutely, even when the evidence said otherwise.
God Himself declares the principle: "Let him who sanctified My name at the sea come and rule Israel." Kingship is the reward for sanctification. The elders who heard Rabbi Tarfon's explanation acknowledged the truth of his derivation — the biblical text itself confirms that Judah's royal destiny was sealed at the shores of the Red Sea, not on a battlefield or in a palace. The crown of Israel belongs to the tribe that was willing to drown in God's name before anyone else would even get their feet wet.