Usually, when Christians think of singing and praise, it is a one way street. People sing to God. People praise God. People exult God. But the Bible tells us of God’s strong emotion towards those who love God. God’s zeal moves God into songs about us.
Zep 3:17 The LORD your God is in your midst, a mighty one who will save; he will rejoice over you with gladness; he will quiet you by his love; he will exult over you with loud singing.
In Zephaniah, God is speaking to Israel. In the first part of chapter 3, God talks about His vengeance on those who have rejected Him. In Israel, only a faithful remnant would be left. They would continue to remain faithful. Over these people God would pour blessings. God states that He will be so enamored with them that God would sing (exult) them.
There is no real reason to take this as some sort of idiom. The text is doubly redundant. God both rejoices and exults over the remnant. This is all in the context of God pouring blessings of this people.
Scattered throughout the Bible are many more descriptions of strong emotion in God. In human beings, our emotions often lead us to song. There is no reason to think God’s strong emotions leave Him stoic.
God writes and sings songs for us.