A type of poison

My friend was given some type of poison that I am unaware of, it makes you do something you don't want to do, like change your mind like for example what happened with him was that he didn't want to leave the job and as soon as someone gave him this small amount of poison, he kept repeating one line "I want to leave this job" and then as soon as he leaves the job, he doesn't remember anything, it's like he blacked out.

Could anyone help me with this poison, what type of poison is this?

A quick look into your question and the symptoms you describe- could be Propranolol, a sympatholytic beta blocker designed for hypertension, anxiety and panic. One of the adverse (side) effects is rather nefarious in nature, and could be utilised by someone who knows what they are doing. This has to do with blocking memories as they form, but before they become imprinted on the mind, a "blackout", as you describe.
I could be wrong, but here is the link for more information:
https://wikipedia.org/propranolol.
best wishes to you and your friend.

I proffered this suggestion because there have been trials as to use (it is a psychotropic drug, designed to alter mood function) in patients with PTSD.

It's almost certainly not a poison and certainly not an herbal substance. Could be some form of drug, or it could be something else entirely. If this hasn't stopped your friend probably needs to be checked by a physician.

This thread has been moved to Misc Topics from Herbalism.

To be honest, he could have a physical health problem that caused this. Any problem that can affect the brain has the potential to cause abnormal behavior. The possibilities are practically endless in that area. Tumor and stroke are the top concerns. Regardless, be it drug abuse or ill health, I suggest your friend seek out a full physical from a doctor and let them know of this experience so they know what to look for.