Charles Ellicott Commentary Psalms 114:2

"Judah became his sanctuary, Israel his dominion." — Psalms 114:2 (ASV)

Judah was. —Better, became. The feminine verb shows that the country is intended, and not the tribe, and the parallelism directs us to think not of the territory of the tribe of Judah alone, but of the whole country. Notice the art with which the name of God is reserved, and the simple pronoun, His, used. (Compare to Exodus 19:6.)