Adam Clarke on Zephaniah 3:17

The Lord thy God - יהוה אלהיך Yehovah Eloheycha, "The self-existent and eternal Being, who is in covenant with you;" the character of God in reference to the Jews when standing in the nearest relation to them.

Is mighty - גבור gibbor, is the prevailing One, the all-conquering Hero. The character which is given to Christ, Isa 9:6 : "His name shall be called אל גבור El gibbor, the prevailing Almighty God."

He will save - Deliver thee from all the power from all the guilt, and from all the pollution of thy sins; and when thus saved "he will rejoice over thee with joy," with peculiar gladness. "He will rest in his love," - he will renew his love. He will show the same love to you that he did of old to Abraham, Isaac, and Jacob.

He will joy over thee with singing - The conversion of the Jews will be a subject of peculiar delight and exultation to God himself! There will be a more than ordinary joy in heaven, when the Jews return to God through Christ. This event cannot be at a great distance; they are as wretched and as ungodly as they can well be. The arms of Christians are open to receive them; and all things are now ready!