Blow the trumpet in Zion, sanctify a fast, call a solemn assembly:
Blow the trumpet - to convene the people (Numbers 10:3: cf. Joel 1:14). The nation was guilty, and therefore there must be a national humiliation. Compare Hezekiah's proceedings in proclaiming a solemn Passover, to which he invited Israel as well as Judah, before Sennacherib's invasion, saying, 2 Chronicles 30:6; 2 Chronicles 30:8-9, "Ye children of Israel, turn again to the Lord God of Abraham, Isaac, and Israel, and He will return to the remnant of you that are escaped out of the hand of the kings of Assyria ... yield yourselves unto the Lord ... that the fierceness of His wrath may turn away from you ... for the Lord your God is gracious and merciful, and will not turn away His face from you, if ye return unto Him."