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.
It was a strange and unreasonable action that the Lord commanded. But strange as it was, Moses did as God commanded, instead of arguing or reasoning with the Lord: ”Why, God? It doesn’t make any sense.” Because Moses obeyed and hit the rock, God was able to provide abundant water.
Our Lord puts a blessing on our obedience to His commands. Just trust and obey. For example, it’s possible for us rationalize, justify, and excuse lying, stealing, adultery, even murder. Instead, we just do as God says because He says so. We don’t resist and ask, ”Why?” like a stubborn child.
There is a possible reason for smiting the rock: it a symbol of the suffering and crucifixion of Christ. The Rock is Christ; the Smiting is the Passion; the Water is Eternal Life. We NT people know that, but Moses couldn’t know that. He didn’t know why he should smite the rock, and he didn’t ask. He just did it. And the result was glorious.
We don’t always know why we should keep the Commandments, e.g., why it is harmful to dishonor parents, not kill, not commit adultery, not steal, not covet, etc. We don’t know the blessings nor the unintended consequences, but we want to obey anyway. Obedience is our response to God. Jesus obeyed; Jesus was stricken, smitten, and afflicted; Jesus gives the living water of eternal life.