1 Corinthians 10:9 We must not put Christ to the test, as some of them did and were destroyed by serpents,
Numbers 21:5-6 And the people spoke against God and against Moses: "Why have you brought us up out of Egypt to die in the wilderness? For there is no food and no water, and our soul loathes this worthless bread." So the Lord sent fiery serpents among the people, and they bit the people; and many of the people of Israel died.
Here we have a stark word. Here we see the Lord testing Israel: "He gave you manna to eat in the wilderness, something your ancestors had never known, to humble and test you so that in the end it might go well with you." [Deuteronomy 8:16]. Yet Paul says that they put Him to the test. A great irony occurs when God is testing us, and we despise His discipline, thereby testing Him.
The children of Israel once again complained about their physical needs -- despising His provision -- and calling manna "worthless bread!" This behavior crossed a line and stands as a serious warning. God's tests are not without purpose. "He humbled you, causing you to hunger and then feeding you with manna, which neither you nor your ancestors had known, to teach you that man does not live on bread alone but on every word that comes from the mouth of the Lord." [Deuteronomy 8:3] Where have we heard that before? What greater life-changing lesson?
Israel was the one nation which received the greatest revelation of God's election, His love, and His miraculous power. This election, however, came with commensurate responsibility. YHVH had revealed Himself in massive, and mighty acts, but it was not for entertainment or just to write a great story. It was to shape a nation into people of great character, patience, endurance, and faithfulness. These characteristics belong to God Himself and they are not optional for His people. He will have a people who exemplifies them. For this reason, the discipline of God is necessarily severe when He is put to the test -- whereby He sent serpents to strike the children of Israel for their sin. And many of them died.
Yet even this terrible object lesson brought greater revelation to Israel, and to all of us as well, as the Lord instructed Moses to erect a serpent on a pole -- so that whoever looked upon it was healed from the serpent's bite! This we now know was a pre-figuration of the cross of Messiah Yeshua (Jesus).
So, how much complaining will our Lord endure? In the beginning, when we are starting out with Him, and because He is patient, probably a lot. Yet, as we grow and He continues to show us His love and faithful care, His expectations of us will increase and His tests will be more stringent. We should cultivate an attitude of patient endurance when He is testing us, lest we find ourselves turning around in bitterness and testing Him. "No discipline seems pleasant at the time, but painful. Later on, however, it produces a harvest of righteousness and peace for those who have been trained by it." [Hebrews 12:11]