He was oppressed, and he was afflicted,
yet he opened not his mouth;
like a lamb that is led to the slaughter,
and like a sheep that before its shearers is silent,
so he opened not his mouth.
He was dragged before the Sanhedrin and the High Priest to be questioned and falsely accused, yet "Jesus remained silent" (Matt. 26:63). When Pilate questioned Him to determine His fate, "He gave him no answer, not even to a single charge, so that the governor was greatly amazed" (Matt. 27:14). He had another chance still when Pilate sent Him to Herod, yet again "He made no answer" (Luke 23:9). Even as He was flogged, struck in the head with a reed, spit upon and mocked Scripture records no complaint escaping Jesus' lips.
Isaiah prophesied that it would be this way. He said the Messiah would march to His death like a lamb is led to the slaughter, silently and submissively. Lambs don't protest because they lack sense. Jesus refused to grumble because He trusted His Father and was willing to endure anything to fulfill God's purpose for His life. Anything for God's glory (John 12:28).
Ultimately that's the problem with complaining, with grumbling against the circumstances of your life. It means that you think God has messed up. Either you don't trust that He knows what He is doing, or you don't think His purposes are worth your pain. Are you willing to endure anything to fulfill God's purpose for your life, to bring Him glory? When you grumble and complain against God, even in your own thoughts, you reveal the outer boundaries of your willingness to follow Him.
Consider how often the people of Israel grumbled, complained and rebelled against God during their journey in the wilderness. God had a purpose for every discomfort and difficulty they experienced. He was teaching His people to trust Him completely. With each trial they had the opportunity to learn to turn to Him for help and watch Him provide for their needs abundantly. Had they submitted to God and learned this lesson well it would have paid great dividends as they went in to possess the Promised Land. Unfortunately, they didn't submit to God. They grumbled and complained, so they continued to struggle for many years to come.
But Jesus is the new and perfect Israel. He gets it right precisely where they got it wrong. He doesn't grumble. He willingly submits. He accomplishes God's will for His life. In only three and a half years of ministry He changed the world forever and He opened a door into the true Promised Land, Heaven above.
God accomplishes great things in and through us by virtue of our suffering, our difficulty, and our discomfort. We are called to emulate Jesus. Let's complain less and trust more. Let's turn to God for strength and deliverance, and trust that He really will cause all things to work together for our good (Romans 8:28). Let's stop grumbling and start praising!