What does the Bible say about murmuring and complaining?

In Jude 16, the scripture describes certain individuals as 'murmurers' and 'complainers,' indicating that they speak against God and His servants. This behavior is rooted in a lack of reverence for God, often manifesting in quiet dissent that can grow into louder expressions of discontent. The text emphasizes that such individuals may appear outwardly righteous but are spiritually dead, akin to the Pharisees who criticized Jesus without real understanding or belief. Ultimately, murmuring is a reflection of dissatisfaction with God's plan and a heart not aligned with His will.