Declare... publish... say. Compare Jeremiah 46:14; Jeremiah 50:2.
Judah. Put by Figure of speech Synecdoche (of Part), for Judah and Benjamin.
Blow ye. Hebrew text reads, "And blow ye": but Hebrew margin, and some codices, with three early printed editions, Aramaean, Septuagint, and Syriac, read without the "And". This is followed by Authorized Version and Revised Version.