Exodus 16:2 "And the whole congregation of the children of Israel murmured against Moses and Aaron in the wilderness:"
The word "murmur" both in English and in Greek (not sure about Hebrew) is an onomatopoeia. Can you imagine the sound of 2 million people murmuring? Its difficult for us to imagine how annoying Moses must have felt dealing with the constant complaining of so many people.
Rather than murmur about what we don't have or the actions of whoever is in charge, we need to focus more on contentment and patience - and using our mouths to say things befitting such attitudes. .
