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.
“When you enter the land which the Lord your God gives you, you shall not learn to imitate the detestable things of those nations. There shall not be found among you anyone who makes his son or his daughter pass through the fire, one who uses divination, one who practices witchcraft, or one who interprets omens, or a sorcerer, or one who casts a spell, or a medium or a spiritist, or one who calls up the dead" (Deuteronomy 18:9-11).
Divining with rods is a form of divination. And, you can see what the Bible lumps that in with.
There is zero scientific evidence that there is any physical mechanism behind divining. So, if there isn't a physical mechanism, then what kind of mechanism makes divining work? The only possible type left is a supernatural mechanism.
In other words, "if" divining works (and I put if in quotes, because I personally believe most people involved in this are simply frauds), then the only reason it works is because there is a supernatural cause--a spirit--moving the rods. But, since the Bible forbids this, we know the spirit moving this isn't God or a holy angel. That leaves only one option: a fallen angel (a demon, the devil, whatever you want to call it).
This is why the Bible condemns divination, because when you get involved in it you are either (1) committing fraud, or (2) teaming up with a demonic spirit (perhaps unknowingly, but still teaming up).