The Book of Zephaniah in Fausset's Bible Dictionary

The bulk of the book forms the introduction to the grand closing consummation under Messiah (Zephaniah 1:2 to 3:8; Zephaniah 3:9-20). I. Threat of judgments (Zephaniah 1:2-7). On whom they shall fall (Zephaniah 1:8-11). Nearness and awfulness of the day of the Lord, and impossibility of escape (Zephaniah 1:12-18). Call to the apostate nation to repentance, and to the meek and righteous to exercise those graces which may avert the day of wrath (Zephaniah 2:1-3). Motive to it: God's coming judgments on Israel's foes, the Philistines, Moabites, Ammonites (the land of which three nations the remnant of Jehovah's people shall possess), Ethiopians, and Nineveh, which shall be a desolation; "He will famish all the gods of the earth (by destroying the nations worshipping them), and men shall worship Him" each in his own house (Zephaniah 2:4-15). The call being slighted and even Jerusalem being unreformed of her filthiness by the judgments on surrounding nations, the just God is constrained to chastise her (Zephaniah 3:1-7). In all this the Chaldaeans' name, the executioners of God's vengeance on Judah, is not mentioned as in Jeremiah, for the latter being nearer the fulfillment prophesies more explicitly. II. After her chastisement Jehovah invites the pious remnant of the Jews to wait upon Him, as He is about to interpose for Judah and Jerusalem against the nations gathered against her (Zechariah 12-14). "The remnant of Israel shall no longer do iniquity. The Lord her God shall rejoice over her with joy, and make her a praise among all people," who in consequence shall "all call upon Him and serve Him with one consent" (Zephaniah 3:8-20). The style is graphic and vivid, and the language pure and free from Aramaisms. Zephaniah 2:14 corresponds to Isaiah 34:11; Zephaniah 2:15 corresponds to Isaiah 47:8; Zephaniah 3:10 corresponds to Isaiah 18:1; Zephaniah 2:8 corresponds to Isaiah 16:6; Zephaniah 1:5 corresponds to Jeremiah 8:2; Zephaniah 1:12 corresponds to Jeremiah 48:11. Romans 15:6 apparently refers to Zephaniah 3:9.

Link: https://bible-history.com/faussets/Z/Zephaniah,+the+book+of/