Commentaire sur Les Psaumes 114:2

Judah became His holy nation He took Judah as the lot of His portion and His sanctity, and even they sanctified His name when they descended into the sea, as the matter that is stated (above 68: 28): “the princes of Judah pelt them with stones.” Similarly, this verse is explained in the Aggadah (Mid. Ps. 114:8): Judah became His holy people, for Nahshon sprang into the sea and said, “I shall descend first,” and that is what [the Psalmist] says: Judah became His holy people.