Hear ye this, O house of Jacob, which are called by the name of Israel, and are come forth out of the waters of Judah, which swear by the name of the LORD, and make mention of the God of Israel, but not in truth, nor in righteousness.
The waters of Judah - spring from the fountain of Judah, (Numbers 24:7; Deuteronomy 33:28; Psalms 68:26, margin.) Judah has the 'fountain' attributed to it because it survived the ten tribes, and from it Messiah was to spring.
Swear by the name of the Lord - (Isaiah 19:18; Isaiah 45:23; Isaiah 65:16.)
And make mention of the God of Israel - in prayers and praises.
Not in truth - (Jeremiah 5:2; John 4:24.)