Water Came Out Of The Rock Despite Disobedience

There was no water for the community, so they assembled against Moses and Aaron. The people quarrelled with Moses and said, "If only we had perished when our brothers perished before the Lord. Why have you brought the Lord's assembly into this wilderness for us and our livestock to die here? Why have you led us up from Egypt to bring us to this evil place? It's not a place of grain, figs, vines, and pomegranates, and there is no water to drink!"
Then Moses and Aaron went from the presence of the assembly to the doorway of the tent of meeting. They fell facedown, and the glory of the Lord appeared to them. The Lord spoke to Moses, "Take the staff and assemble the community. You and your brother Aaron are to speak to the rock while they watch, and it will yield its water. You will bring out water for them from the rock and provide drink for the community and their livestock."
So Moses took the staff from the Lord's presence just as he had commanded him. Moses and Aaron summoned the assembly in front of the rock, and Moses said to them, "Listen, you rebels! Must we bring water out of this rock for you?" Then Moses raised his hand and struck the rock twice with his staff, so that abundant water gushed out, and the community and their livestock drank.
But the Lord said to Moses and Aaron, "Because you did not trust me to demonstrate my holiness in the sight of the Israelites, you will not bring this assembly into the land I have given them." (Numbers 20:8-12 CSV)

God had asked Moses to speak to the rock but Moses struck the rock twice. Please take note of two things:

1. God's severity toward Moses and he was punished for striking the rock twice;
2. God's kindness to the Israelites and brought water out of the rock despite their unbelief.

Thus the mercy (which is injustice) of God often confuse people when their evil deeds bring prosperity instead of punishment.

Because the sentence against an evil deed is not executed speedily, the heart of the children of man is fully set to do evil. (Ecclesiastes 8:11 ESV)

Note then the kindness and the severity of God: severity toward those who have fallen, but God's kindness to you, provided you continue in his kindness. Otherwise you too will be cut off. (Romans 11:22 ESV)

The Lord is not slow to fulfil his promise as some count slowness, but is patient toward you, not wishing that any should perish, but that all should reach repentance. (2 Peter 3:9 ESV)