The clause declares the Lord
appears frequently throughout the prophets, normally in the middle or at the end of a saying from the Lord to indeed emphasize its origin. Zephaniah uses the clause five times (Zephaniah 1:2, Zephaniah 1:3, Zephaniah 1:10; Zephaniah 2:9; Zephaniah 3:8). This formula stamps the seal of divine authority on what has been proclaimed…. If the prophet is to say something that appals (1:2–3), shocks (1:10), horrifies (2:9), or seems too good to be true (3:8), he needs to be sure of his ground; he needs the authority of the divine word.
1
2 “I will utterly sweep away everything from the face of the earth,” declares the LORD.