Contradiction with Exodus 17:6
In Exodus 17:6, God instructs Moses to strike the rock to bring forth water, whereas in Numbers 20:7, God tells Moses to speak to the rock.
Exodus 17:6: Behold, I will stand before thee there upon the rock in Horeb; and thou shalt smite the rock, and there shall come water out of it, that the people may drink. And Moses did so in the sight of the elders of Israel.
Contradiction with Numbers 20:11
In Numbers 20:11, Moses strikes the rock instead of speaking to it as instructed in Numbers 20:7, leading to a different consequence.
Numbers 20:11: And Moses lifted up his hand, and with his rod he smote the rock twice: and the water came out abundantly, and the congregation drank, and their beasts [also].
Contradiction with Numbers 20:12
Numbers 20:12 shows the consequence of Moses not following God's command to speak to the rock as instructed in Numbers 20:7.
Numbers 20:12: And the LORD spake unto Moses and Aaron, Because ye believed me not, to sanctify me in the eyes of the children of Israel, therefore ye shall not bring this congregation into the land which I have given them.