God takes note of the discontent of our hearts--as well as the murmuring of our lips.
Not only is discontent a grievous sin against God, but it unfits the Christian for the discharge of holy duties, preventing the exercise of those graces which are necessary in order thereunto.
It silences the lips of supplication, for how can a murmurer pray?
It destroys the spirit of submission, for complaining is a fretting against the Lord.
It quenches faith, hope and love.
Discontent is the very essence of ingratitude, and therefore it stifles the voice of thanksgiving.
There cannot be any rest of soul, until we quietly resign our persons and portions to God's good pleasure.
Discontent corrodes the strings of the heart, and therefore it arrests all growth in grace.
Discontent is usually over temporal matters, and this is a sad intimation that material things are sought after more eagerly than are spiritual things. It argues a lack of confidence in the care of our heavenly Father to provide for us the things which are needed.
"How long shall this wicked congregation grumble against Me? I have heard the grumblings of the people of Israel, which they grumble against Me!" Numbers 14:27
"Do all things without grumbling and complaining!" Philippians 2:14
"Keep your lives free from the love of money and be content with what you have, because God has said: Never will I leave you; never will I forsake you." Hebrews 13:5