Is it illegal to suspend someone without clear reason or for talking?

Good day,today i had an incident at work and was wondering what where your thoughts and do i have a case? The story goes like this, i go into work and as soon as i get there my manager(lindsey) says they want to talk to me upstairs(First time this has ever happened) and so i go upstairs and they sit me down to tell me im being suspended for talking to co workers about drugs. I asked them who said it and what did i say exactly. all they said was employees(no names just generic answer) told us and you where talking about drugs, when i asked what did i say all they said is that i was talking about drugs. They let me make a statement i put i was talking about psychedelics and how they could help people with addictions and how they helped me in the past. later when i asked for my statement eric(deparment manager) said i could not have it because it was Heb property. This case just seems like it was planned to get rid of me because they gave me very vague answers and gave me no names to who said what. not only that but they said in the book they have a strict law about drugs but did not show me anything all they said was a vague reason why they suspended me(will most likely get fired) and a 2 page paper to write a statement on the indecent. I honestly don't even know what i did, it was not a work related issue it was just because i talked so i was wondering what where your thoughts on this and thank you for taking the time to read this and reply, Your time and advice is greatly appreciated.