Christians are to offer sacrifices to God, among these sacrifices is the sacrifice of praise, and our sacrifices are meant to please God
Consider the sacrifice which Jesus made upon the cross. Our sacrifices must emulate the sacrifice of Christ, for by his cross he became the author and finisher of our faith
Christ's sacrifice was an act of obedience to God's counsel, and thus it pleased God. We must emulate this in our worship
Cain offered a sacrifice which displeased God. God tried to reason with him, but he could not understand why God rejected his offering, yet accepted his brother Abel's, so in jealousy he murdered his brother
Nadab and Abihu offered a sacrifice which displeased God, and they suffered the penalty of death
In hindsight, we realise that the offerings of Nadab and Abihu, and Cain, were rejected because they were not "types" (holy symbols) of Christ's sacrifice. But the blunder would not have been made, had the worshippers followed God's command, instead of
God's counsel to us, is that our sacrifice of praise should be "the fruit of lips" in other words, "singing and making melody in your heart to the Lord"
Some people want to add the use of musical instruments to this sacrifice of praise, but they have no authority or counsel from God. In the brackets following, I quote every passage where God commands Christians to use musical instruments in their sacrifice