“And the people contended with Moses and spoke, saying: “If only we had died when our brethren died before the LORD!”Numbers 20:3 NKJV
This had happened before. The Israelites murmured about a lack of water, having no meat to eat, that their conditions in Egypt were better, etc. God had judged them and also demonstrated to them that He was able to provide much more than they can imagine. Yet, they murmured again.
The conditions that they experienced were probably worst than what we can imagine. Yet, the bible did not regard this appropriate for complaint. Perhaps the reason was because they ought to have raised it respectfully in prayer. Interestingly, that was exactly what Moses did when he heard the complaints of the Israelites. And God responded immediately to his prayer.
This is a reminder to us that God is omniscient. He knows our needs even before we raise it to Him. If we murmur instead of pray when we encounter our needs, we are in effect denying His omniscience. Hence, we sin when we murmur. Let us remember that God is sovereign and knows our every need. He delights in us approaching Him like little children, expressing our needs and trusting that He will provide. He is our Heavenly Father, ruler of the universe. Let us turn to Him for all our needs.